The Mexican cotton boll weevil

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Material Information

Title:
The Mexican cotton boll weevil
Series Title:
Bulletin / United States. Division of Entomology ;
Physical Description:
116 p., 16 leaves of plates : ill. ; 23 cm.
Language:
English
Creator:
Hunter, W. D ( Walter David ), 1875-1925
Hinds, W. E
Publisher:
U.S. Dept. of Agriculture, Division of Entomology
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Boll weevil   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 113-116).
Statement of Responsibility:
by W.W. Hunter and W.E. Hinds.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029640337
oclc - 22617266
lccn - 06000459
Classification:
lcc - SB818 .B85 no.45 1904
ddc - 595.7
bcl - 48.63
System ID:
AA00018937:00001

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Bul 45, Div. of Entomology, U. S. Dept. of Agriculture.


DEVELOPMENTAL STAGES AND WORK OF THE BOLL WEEVIL. ||
Fig. 1, Cotton boll weevil; fig. 2, weevil feigning deitht: fig. :. two eggs and feeding excavation
in a square: fig. 4, full--nr m n larva: fig. 5, ]mliu. ventral view; fig. 6, pupa. ide \it.iw; fig%.. 7-9
show trnin.foriimti,,n taking place within square: fig. 7. lar\.-'. full grown: rig. 8, lpupa: fig. 9.
ailult: rig. 10, weevils fteling on boll: fig. 11. larva developing in boll. kFigs. 1-10. nattiural A
size: tihg. 11, two-thirds natural size.-Original.)
I

h


PLATE I.








U. DPARMET OF AGRICULTURE,
DIVIION F ENOMOOGY-BULLTINNo. 45.









TTTON BOLL YEEYIL.









THE DIRECTION OF THE ENTOMOLOGIST
BY

W. D. HUNTER and W. E. HINDS.















WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1904















LETTER OF TRANSMITTAL.



U. S. DEPARTMENT OF AGRICULTURE,
DIVISION OF ENTOMOLOGY,
Wacshington, D. C., February 20, 1904.
SIR: I have the honor to transmit herewith for publication an
account of the Mexican cotton boll weevil, prepared under my direc-
tion by Messrs. W. 1). Hunter and W. E. Hinds, special field agents
of this Division. Mr. Hunter has been engaged for three years in
investigations of this very important injurious insect, his work extend-
ing all through the infested portions of Texas and to some extent into
Mexico. Mr. Hinds for two years has been devoting his whole time
to this subject, having been stationed for the most part at Victoria,
Tex., in charge of laboratory work. The bulletin as a whole is a
remarkably careful and complete treatment of the entomological
aspects of the investigation. It seems to me as complete a treatise of
the life history of a single species as has ever been published. The
necessity for the most perfect knowledge of every detail of the habits
of this great enemy to the cotton crop must be obvious, since only
upon such perfect knowledge can we authoritatively base remedial
work and can we authoritatively indicate the uselessness of many of
the remedies proposed by ingenious and inventive persons. The six-
teen half-tone add other plates and six text figures are an essential
part of the report.
I recommend the publication of this paper as Bulletin No. 45 of
this Division.
Respectfully, L. 0. HOWARD,
Entomologist.
Hon. JAMES WILSON,
Secretary of Agriculture.
















P R !E F AxC,"



The Mexican cottolln boll weevil (An-l/1noulus <'r(Inlis Boll.) lJis th11
unique record of develol)ingll in less titan twenty years frm, a inost,
obscure species to undoubtedly one of the Iliost ilinportalt economic-
ally in the world. It was first brought to the attention ofr tl, e I)ii-
sion of Entomology as an enemy of cotton ini Texas in 1894. Before
it had invaded more than half a dozen counties in the extreme southern
portion of Texas several entomologists were sent to the region in con-
nection with this work. Enough was soon discovered to indicate tlhe
most feasible plans for avoiding damage by the pest. These original
plans, based upon investigations of the life history of tile insect, with
modifications, for the most part due to climatic conditions in regions
quite dissimilar to thlie lower portion of Texas, are still thle basis for
all that is known in combating the pest. However, at that time it
was necessary to pay particular attention to the immediate economic
phases of the problem, and a detailed study of the habits of the insect
was impossible. In 1902, by the aid of a special appropriation by
Congress, it became possible to establish a complete field laboratory
in the portion of Texas in which the weevil had been known to exist
at that time for about eight years, where a careful investigation could
be conducted regarding the points in the life history of tlie pest that
offered even remote chances of suggesting means of avoiding damage.
The results of the work at this laboratory that have been of more
immediate economic bearing have already been published in farmers'
bulletins of this Department. However, as will be seen from the fol-
lowing pages, a very large mass of information concerning all tlhe
habits of the boll weevil has been accumulated. Not only on account
of the great economic importance of the problem and the demand for
information from numerous quarters concerning the biology of the
pest, but also on account of the fact that the methods followed in, this
work have been to some extent original, and may be of use in con-
nection with the investigation of other insects, it is thought advisable
to publish a great number of the observations that have been made.
The historical and economic features, to which reference has been
made elsewhere in the publications of the Division, are included to
bring together in convenient form practically all that is known regard-
3






4.,i
........ - .,...........



ing the species. Much information obtained by the earlier investi-
gators of the Division of Entomology, Dr. L. 0. Howard, Mr. C. L. i
Marlatt, Mr. C. II. T. Townsend, and Mr. E. A. Schwarz, has been
used. On account of the painstaking character of the work of Mr. I
Schwarz, and his intimate knowledge of related species, his reports, I
largely unpublished, have been found especially valuable. In pre-
senting this work the authors have taken care to state fully the data I
furnishing the basis for the various conclusions. Under each impor- 1
tant heading will be found, first, a description of the methods and
apparatus employed; second, a full and in many cases tabular state-
ment of observations; third, the obvious conclusions. Care has con- .
stantly been exercised to avoid errors likely to result from artificial i
conditions in the laboratory. A large part of the work of the past
year was in ascertaining how closely laboratory results corresponded
to the actual conditions in the field. The writers have on many occa- .
sions been surprised to discover how close the correspondence is, and
consider that the demonstration on a large scale of the possibility of ,
accurately determining the details of the life history and habits of an
insect by laboratory investigations is by no means the least important
of the results of the investigation.
The laboratory work which has led to this paper was planned origi-
nally by the senior author, who has also supervised the later develop-
ments of it. However, practically all the labor of conducting the i
experiments and observations has devolved upon the junior author,
who has suggested from time to time many important modifications of
the original plan. Specifically, all of the bulletin except the first por-
tion, dealing with historical matters, the destructiveness of the pest, ?
and the prospects, and the last portion, dealing with methods of com-
bating it, was written by the junior author, although revised in some
particulars after it had been submitted by him. The illustrations
used are from photographs taken for this work by the junior author,
with the exception of the text figures and the illustrations of insects
often mistaken for the boll weevil, of which those marked "original"
are, with one exception, from drawings prepared by Miss L. L. How-
enstein, one of the artists of the Division of Entomology.










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CONTEr NT S.


Page.
General considerations-......... .....-...............----------- 11
Historical -----------.......-----.----------.-------......--------------..------ 11
Destructiveness----- .---.---.--.----------.-------------.....---......---------- 14
Territory affected----------------------------------------- 16
Prospects---- --------------------------------------------------18
Life history------- -------------- ---------------------------------- 20
Summary 0------------- ---------------------------------------20
Theegg ---------- -------------------------------------------- 20
Embryonic development --------- -----------------------------21
Length of egg stage.-----..------....---.---.------------------------- 21
Hatching----------------- -- ---------------------------
Eating of eggs deposited outside------------- ---------------- 2-
Percentage of eggs that hatch--------------- ------------------23
The larva---..-- - - - - - - -----.-----... -------- .... ... .-....-.- 23
Description ---....-------......----.----.------------.----------------- 23
G row th .... .24.......-. .- ... ... . .. -.--- . ......- .. .. ..- 24
Molts..--------------.--...... ------------ --------------------.------ 24
Process of molting .-.---------------------------.-------------- 24
Length of larval stage -------------- --------------------------25
Pupal cells in bolls --. -------------------------- --------------- 26
Pupation ...-..--------------------------------------------------- ........................ 26
The pupa.......----------------------------------- ...------------------- ................. 26
Length of pupal stage ---------------------------------------- 27
Effect of burying squares upon pupation and the escape of adults- 28
The adult------------------............. ------------------------------ ------ 29
Before emergence -------.--- ----...-------------- -------------- ....- 29
Emergence ---------------------------------------------- --- 29
Changes after emergence -.----------- -----------.-----...---------- 29
Size of weevils- ..------------------...------..... 30
Relation of size to food supply ---- -.------------...----------- 30
Weight of adults ----------------------- .................. 30
Color-------------------------- ----------------------------31
Size and color not indicative of sex -----.......-.---.--..----.----.----------- 31
Proportions of the sexes------------------------- ------------- 32
Length of life upon squares ------.--- ..... --.-..---------------. 33
Length of life on bolls alone ---------.------.. ...---.----------------- 34
Length of life on cotton leaves alone ---- --- -- --- 34
Length of life with sweetened water and with molasses - 35
Length of life without food, but with water -------------------- 35
Length of life without food or water ----------------------------35
Cannibalism -------- --------------------------------------- 36
5






6

Page.
Habits -- ----- ---- -- --- --- -- 36
Food habits ----.....--.----------....... ---... .--.------...-------.. 37
Larval --------..-. .....------------------------------------ ......... ...... 87
Adult- .--.----...---------------..---..----------------------7.. 7
Male ---------9----------- ------------------------------ 39
Female----------- .. ..----.------.---.----..---------.....---..--------- 39
Males and females together -----------....-------------------..................... 40
Feeding of hibernated weevils on early cotton -------------------40
Increase in leaf area of cotton ----.----..-...-----------------------.............. 41
Effects of feeding upon squares and bolls ------------------------- 48
Destructive power by feeding ----------------------------------- 44
Susceptibility of various cottons ---------------------.----.. ------. 44
Has the weevil any other food plant?-...-.----.---.-------.....---------. 47
Insects often mistaken for the boll weevil -------------------------- 48
Is cotton-seed meal attractive? -------------------------...----------- 50
Laboratory observations -------..-------------------------- ----- 50
Field tests ----.------.---.-----------------------------.------. 51
The possibility of baiting weevils with sweets ----------------------- 52
Attractiveness of various sweets.---------.. ----------------------. 52
Attractiveness to hibernated weevils in laboratory -----------53
Influence of sweetened water upon feeding of weevils on cotton
plants .-..---------- ------.---.-----... -- 54
Field tests for hibernated weevils, using pure molasses ----------- 55
Feigning death ---.---.-.-------------.---.----.-----------------.... 56
Reproduction -----.-------- ---------.. .. ....-....-.. 56
Method of making field observations upon work of weevils ------------ 56
Fertilization..------- ------.. ---------------------.------------ ..... 57
Age of beginning copulation --...--------....--------..---------- 57
Sexual attraction and duration of copulation --------------------57
Duration of fertility in isolated females.-------..----------------- 58
Oviposition -.....- -------------------------------------------------. ...... 58
Age of beginning oviposition -------..--.------------------------. 58
Examination of squares before oviposition --.... ------------ 59
Selection of uninfested squares for oviposition ------------------- 59
SLaboratory observations -.-------------. ---------.----------. 60
Field observations -------. -------------------------------------.. 61
Activity of weevils in different parts of the day------------------ 63
Place of egg deposition -.-----.----..----.-------.. --------------.- 65
Position of weevil while puncturing for oviposition --------------- 65
The act of oviposition_---- ----------------------------------- 66
Time required to deposit an egg -------------------------------- 67
Rate of oviposition-average, maximum --------------- ......--.---.. 68
Stimulating effect of abundance of squares on egg deposition------ 69
Relation of warts to oviposition --------------------------------- 69
Effects of oviposition upon squares-flaring, falling -.------------- 70
Period of oviposition------ -------------------------------- 72
Does parthenogenesis occur? --------------------------------- 72
Development ..------------------....------...-------------------------- 73
Percentage of weevils developed from infested squares.--------------- 73
Development of weevils in squares which never fall ---------------- 73
Length of life cycle ..-------.-- -----.. -. .. .----.. -------- 74
Broods or generations---....--------------------------------_------- 75










Develtdopiment -( tinild.
Thernmal influMence 'p )n activity id development 77
Laboratory xlrimielIt, in veffet. of tem.ipratur l)E un loco)ni itivi
activity - MO
Hibernation .-...... MO
Length of hiln-rnation period 82
Apparently favorable cond(litions f)r hiblernation .. 83
Perct'ntage of weevils hibernating successfully ..... 83
Seasonal history -- -. .. 84
Emergency from lhiilk'rnatioM ..4 ...... 84
Apparent dependenrce of reproduction upon food obtained from isquares. 85
Progress of infestation in fields -... .- .... .-... 8
Weevil injury r. square production-- .--..-- ---------- 88.. S
Relation of weevils to top crop ---------------------- .... ------- (
Some reasons for early destruction of stalks .................... 92
D issem nation - . - - .. . . . - -. ................. 94
Weevils in seed houses at ginneries-- ...-.....-..-... -----.....--.- 94
Natural control .......... --------------------.-- -------------------------------- . 95
Mechanical control - -----.-...-.------------- 95
Pilose obstacles to weevil progress ----. -. .. .. .- .. -- --. 95
Destruction of larvae and pupae in bolls and squares )by al)bnormal
plant grow th- . .. ... ... ......... .... ... . ...-- 96
Climatic control -- -...-. .-------- -...-------- -. 97
Influence of climatic conditions upon weevil multiplication and
injury ..- -------------------------------------------------- 97
Effect of rains upon development of weevils -.--.--- --.. -. 98
Effects of wet winter weather on hibernating weevils --------------99
Effects of overflows in fields -----------------------------------99
Laboratory observations upon time weevils will float and endure
submergence --- ------------------------------------------ 100
Probabilities as to influence of climate on weevils in cotton regions
not now infested .- --------- -. ----.. . .. 101
Diseases .---.. ---- ------------------------------------------------ ... 104
Parasites ---------------- --... -..----- ------- ---------- -- -.. 105
Breeding of parasites --... -..--....--. .... 105
Pediculoides veni tricosu s --- ------ --- -------- 107
Predatory enemies --------------.... --------------------------------- 109
In sects .. ... ... ... .... ... ....... ..... .... ....... 109
Birds .... ---------------- ....... ......... ... ..--------------- .......... ----... ------------------. 110
Methods of combating the weevil -. -.--.. ---....------------...... 110
Cultural methods......... -.....----------- --------- --- 111
Futile means ......... 112
Bibliography ... -----------.--------.- -.--.----------------- -----..... 113














ILLUSTRATIONS.


PLATES.


PLATE I.


Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.


1.-Cotton boll weevil ----------------...---------
2.-Weevil feigning death----------------------
3.-Two eggs and feeding, excavation in a square - -
4.-Full-grown larva ----------------------------.
5.-Pupa, ventral view ---------------------------
6.-Pupa, side view ----------- --------------
7.-Larva, full-grown--------------
8.- Pupa .. .... -----. --. ...---.. .....--- .--.-----
9.-Adult ---- ---- ---- ------
10.-Weevils feeding on boll --------------------
11.-Larva developing in boll ------ ------------


Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece
Frontispiece


II. Fig. 12.-Collection showing life history and work of boll weevil -


In. Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.

IV. Fig.
Fig.
Fig.
Fig.

Fig.
Fig.


13.-Two weevils feeding on a square---------------------
14.-Egg isolated ----------------------------------------
15.-Full-grown larva in square--------------------
16.-Full-grown larva isolated ---------------------
17.-Pupa..---...--.- ----.-. ----.. -----------
18.-Adult just transformed --------------------------
19.-Large larvwe in large boll -------------------------
20.-Pupal cell in boll broken open --------- -----------.

21.-Emergence hole made by weevil in square -------------
22.-Weevil escaping normally from boll -----------------
23.-Apparatus used in breeding weevils------------------
24.-Larva destroying the ovary and preventing bloom in
large square---------------------------------------
25.-Leaf fed upon by weevils in confinement --------------
26.-Emergence hole of weevil from boll which never opened -


V. Fig. 27.-Larva in square, ovary untouched-----------------
Fig. 28.-Large and small larvae in boll----------------------
VI. Fig. 29.-Square much fed upon-------------------------
Fig. 30.-Distorted bloom, caused by feeding upon large square -
VII. Fig. 31.-Blooms distorted by feeding punctures, open but imper-


Fig.
Fig.

VIII. Fig.
Fig.
IX. Fig.
Fig.
8


fect -.----------- --- ----------- --- ---- ------- --- -
32.-Small boll riddled by feeding punctures ---------------
33.-One lock of boll destroyed by feeding punctures -------
34.-External appearance of large boll much fed upon
35.-Internal appearance of same boll ...-------------------
36.-Cages used to confine weevils in field -----------------
37.-Plant showing tagged squares from cage work---------









PL


ATK X.


Fig. :iN.-Boll showing two l'cks ddestroye.d Iby twi, ftelding
punturt.r.s iiul'l, lby aii iale wtvil
Fig. :In3.-Sia tre slhowiiitng extnuil Ipp)iILr-anc.' f t(i f ; egg Illmr-
tunrs
Fig. 10.-W-,art fomled 0i n stiil' of Hqrnii4' in llhaliing iin gg pinm'-
lure'
Fig. 41.-E.gg depiosit'ed o0 inside of c(alrpl)l of .'i Ill
Fig. 42.-Normal and flared s(iar.es


XI. Fig.
Fig.


XII. Fig.

Fig.
Fig.
Fig.


43.-Three large larv'e in a holl
44.-Four pupal cells from l)olls ()n left cnupared with four
cotton seeds on right .. ....
45.-Device used to test attraction of molasses in the field
in spring- ---------------------..-
46.-Fallen squares on -ground iln field ---..-----.
47.-Squares dried and still hanging upon the plant..
48S.-Device used to test relative attractiveness to weevils
of American and Egyptian squares --- --


XIII. Fig. 49.-Device used to test effect of templ)eratnre upon weevil
activity ..... ------------------------------------..---.
Fig. 50.--Comparison of pilosity on King (at left) and '" Mit
Afifi (at right) stems ----------. ---.------- ---.
Fig. 51.-Locality found very favorable to hibernation of many
weevils....---------------- -------- --.--------.----

XIV. Figs. ;-2 and 53.-Mexican cotton boll weevil (Aitlhioomuis
grandis) ------------------------ ---
Fig. 54.- Li.rits sp -- - - - - ---------------------- --- . -
Fig. 55.-Acorn weevil (Balai, in,,s it i iforim is auct. ) a. female.
dorsal view: b, same. lateral view: e, head, snout.
and antenna of male ----..---------.----------- -...
Fig. 56.-Apple curculio (Coccoto rits scn fella ris) -... -.. ...-.---
Fig. 57.-Plum gouger (Anthonoms pru icilda) ---...... -.. ...---
Fig. 58.-Desmoris scapalis --------------------. -- -- -.

XV. Figs. 59 and 60.-Transverse Baris (Baris fransr.rs) -.... ....
Fig. 61.-Centr-is -pen icells -----
Fig. 62.-Coffee bean weevil (Ar(ecerus fasicicdhati s): a. larva:
1. beetle; c. pupa----------- -------------------
Figs. 63 and 64.-Cihalcoderinmus (ceiis -----------

XVI. Figs. 65. and 66.-Sharpshooter (Homalodisca triqetra) -......-
Fig. 67.-Cotton stainer (Dysdercits suturellus) -------- --
Fig. 68.-Cotton stalk borer (Atu.ria crypta)................
Fig. 69.-I-nbricated snout-beetle (Epitcrti s ii, brica tii.)
Fig. 70.-A snapping beetle (Monocrepidius vespertina us).....

TEXT FIGURES.

FIG. 1. Map of area infested by weevil ..-------------.....................
2. Mexican boll weevil, head showing rostrum and antennae .
3. Diagram showing activity of 5 female weevils ..------------..
4. Bracon mellitor -.-----.-------------------- .......-------...................
5. Enemy of boll weevil, Pedicidoides rent rieosus ... ... -
6. Solenopsis debilis var. fexana -- ------------- ----


17
38
64
106
107
109




.. -.-............w.














THE MEXICAN COTTON BOLL WEEVIL.



GENERAL CONSIDERATIONS.
HISTORICAL.
There is very little certainty regarding the history of the Mexican
cotton boll weevil before it came to the attention of the D)ivision of
Entomology in Texas in 1894. The species was described by Bolhe nman
in 1843 from specimens received from Vera Cruz, and it was recorded
by Suffrian in 1871 as occurring at Cardenas and San Cristobal in
Cuba. Written documents in the archives at Monclova, in the State
of Coahuila, Mexico, indicate that the cultivation of cotton was prac-
tically abandoned in the vicinity of that town about the year 1848, or
at least that some insect caused very great fears that it would be nec-
essary to abandon the cultivation of cotton. A rather careful inves-
tigation of the records makes it by no means clear that the insect was
the boll weevil, although there is a rather firmly embedded popular
notion in Mexico, as well as in the Southern United States, that the
damage must have been perpetrated by that species. As far as tlhe
accounts indicate, it might have been the bollworm (Heliothis ,rni-
ger) or the cotton caterpillar (Aletia argillacea).
From the time of the note by Suiffrian regarding the occurrence of
the weevil in Cuba in 1871 up to 1885 there has been found no pub-
lished record concerning it. In 1885, however, C. V. Riley, then
Entomologist of the Department of Agriculture, published in tlhe
report of the Commissioner a very brief note to the effect that Anthio-
nomiuS grandis had been reared in the Department from dwarfed cot-
ton bolls sent by Dr. Edward Palmer from northern Mexico. This is
the first account associating the species with damage to cotton. The
material referred to was collected in the State of Coahuila, supposedly
not far from the town of Monclova. Thle exact date at which the
insect crossed the Rio Grande into Texas is as uncertain as the means
whereby this was accomplished. All that can be found, which is
mostly in the form of testimony of planters in the vicinity of Browns-
ville, indicates that the pest first made its appearance in that locality
about 1892. In 1894 it had spread to half a dozen counties in the
Brownsville region, and during the last months of the year was
brought to the attention of the Division of Entomology as an impor-
tant enemy of cotton. Mr. C. H. T. Townsend was immediately sent






12


to the territory affected. His report was published in March, 1895.
It dealt with the life history and habits of the insect, which were
then completely unknown, the probable method of its importation,
the damage that might result from its work, and closed with recom-
mendations for fighting it and preventing its further advance in the
cotton-producing regions of Texas. It is much to be regretted that
the State of Texas did not adopt at that time the suggestion made by
the Division of Entomology that a belt be established along the Rio
Grande in which the cultivation of cotton should be prohibited, and
thus cut off the advance of the insect.
The events of the last few years have verified the prediction of the
Division of Entomology in regard to the advance made and the dam-
age caused by the insect.
In 1895 the insect was found by the entomologists, who continued
the investigation started the year before, as far north as San Antonio
and as far east as Wharton. Such a serious advance toward te
principal cotton-producing region of the State caused the Division-to
continue its investigations during practically the whole season. The
results of this work were incorporated in a circular by Doctor Howard,
published early in 1896, in both Spanish and English editions.
An unusual drought in the summer of 1896 prevented the maturity
of the fall broods of the weevil, and consequently there was no exten-
sion of the territory affected. It should be stated in this connection
that the region from San Antonio to Corpus Christi and thence to
Brownsville will frequently pass through similar experiences, which
will be quite different from anything that may be expected to occur
in regions where the rainfall is more certain. In 1900 as well as in
1903, in all or part of the region referred to, the numbers of the weevil
were reduced by climatic conditions, principally a scanty rainfall, so
that they were comparatively unimportant factors. During 1896 the
investigations were continued and the results published in another
circular issued in February, 1897. This circular was published in
Spanish and German, as well as English editions, for the benefit of the
very large foreign population in southern Texas.
The season of 1897 was in many respects almost as unfavorable as
that of 1896, although the pest increased its range to the region about
Yoakum and Gonzales. Although this extension was small it was
exceedingly important, because the richest cotton lands in the United
States were beginning to be invaded. The problem had thus become
so important that Mr. Townsend was stationed in Mexico, in a region
supposed to be the original home of the insect, for several months to
discover, if possible, any parasites or diseases that might be affecting
it, with the object of introducing them to prey upon the pest in Texas.
Unfortunately nothing was found that gave any hope of material
assistance in the warfare against the weevil.
The season of 1898 was very favorable for the insect. Bastrop,






13

Lee, tiand Iurleson counthies be(ame iIVadIed, a1!d so011lm isolated .,ln,-
nies were found across the lrazos River, in Waller and itlazOl s .tJ'1111-
ties. Investigations by the Division of Entomology were otlli.ini[lel,
and a summary of the work, dealinlig especially rwitll Xperim(-I ts
conducted by lIr. C. L. Marlatt in the spring of ,1896, was pjldlislied
in still another circular. At this time the legislature of the Stale of
Texas made provision for the appointment of a State ('I.toniololgist
and provided a limited appropriation for an investigations of 1imeains
of combating the boll weevil. In view of this fact tlhe D)ivision of
Entomology discontinued, temporarily, the work that hiad b)een carried
on by having agents in the field almost constantly for four years, and
all correspondence was referred to the State entomologist; but,
unfortunately, the insect continued to spread, and it soon became
apparent that other States than Texas were threatened. This caused
the work to be taken up anew by the Division of Entomology in
1901, in accordance with a special appropriation by Congress for an
investigation independent of that being carried on by the State of
Texas and with special reference to the discovery, if possible, of
means of preventing the insect from spreading into adjoining States.
In accordance with this provision an agent was sent to Texas in
March and remained in that State until December. Ile carried on
cooperative work upon eight of the larger plantations in the weevil
region. The result of his observations was to suggest the advisability
of a considerable enlargement of the scope of the work. It had been
found that simple cooperative work with the planters was exceedingly
unsatisfactory. The need of a means of testing the recommendations
of the Division of Entomology upon a large scale, and thereby furnish-
ing actual demonstrations to the planters, became apparent. Conse-
quently, at the suggestion of the Department of Agriculture, provision
for an enlargement of the work was made by Congress. Agreements
were entered into with two large planters in typical situations for test-
ing the principal features of the cultural system of controlling the
pest upon a large scale. In this way 125 acres at Victoria and 200
acres at Calvert were employed. At the same time the headquarters
and laboratory of the special investigation were established at Vic-
toria, and such matters as parasites, the possibility of poisoning the
pest or of destroying it by the use of machines, as well as investigat-
ing many of the features of its biology that were still absolutely
unknown, were given careful attention by a specially trained assistant
whose services were procured for that purpose. The results of the
field work for this year were published in the form of a Farmers'
Bulletin entitled "Methods of Controlling the Boll Weevil; Advice
Based on the Work of 1902;" but on account of the late date of the
establishment of the laboratory (June), and the consequent incom-
pleteness of many of the records, it was not thought advisable to
publish anything concerning the laboratory investigations. During








this season cooperation was carried on with the Mexican commission
charged with the investigation of the boll weevil in that country, which
was arranged on the occasion of a personal visit of Dr. L. 0. Howard
to the City of Mexico in the fall of 1901. Specimens of parasites were
frequently exchanged, and through the courtesy of Prof. A. L.
IIerrera, chief of the Mexican commission, an agent in charge of the
investigation in Texas visited the laboratories at the City of Mexico
and Cuernevaca, where a study was made of the methods of propa-
gating parasites, especially Pediculoides centricosus Newp. A large
number of specimens of this mite was brought back to Texas, where
they were carried through the winter successfully and used in field
experiments the following season.
The favorable reception by the planters of Texas of the experi-
mental field work conducted during this season, with the increased
territory invaded by the pest, brought about an enlarged appropria-
tion for the work of 1903. By enactment which became effective on B
the 4th of March $30,000 was placed at the disposal of the Division of I
Entomology. It thus became possible to increase the number and size -
of our experimental fields as well as to devote more attention to the
investigation of matters suggested by previous work in the laboratory.
Seven experimental farms, aggregating 558 acres, were accordingly .
established in as many distinct cotton districts in Texas. Despite :
generally very unfavorable conditions the results of this experi-
mental work demonstrated many important points. The principal ,
ones are detailed in Farmers' Bulletin No. 189 of this Department.

DESTRUCTIVENESS. '
Various estimates of the loss occasioned to cotton planters by the :
boll weevil have been made. In the nature of the case such estimates L
must be made upon data that is difficult to obtain and in the collec-
tion of which errors must inevitably occur. There is, of course, a
general tendency to exaggerate agricultural losses, as well as to attrib-
ute to a single factor damage that is the result of a combination of
many influences. Before the advent of the boll weevil into Texas
unfavorable weather at planting time, summer droughts, and heavy
fall rains caused very light crops to be produced. Now, however, the
tendency is everywhere to attribute all of the shortage to the weevil.
Nevertheless, the pest is undoubtedly the most serious menace that
the cotton planters of the South have ever been compelled to face, if
not, indeed, the most serious danger that ever threatened any agri-
cultural industry. It was generally considered, until the appearance
of the pest in Texas, that there were no apparent difficulties to prevent
an increase in cotton production that would keep up to the enlarging
demand of the world until at least twice the present normal crop of
about 10,500,000 bales should be produced. Now, however, in the
opinion of most authorities, the weevil has made this possibility very








dou1 tfulh alt llougli tile lirst fean'rs ej ,te'itaini.ed1 i Il 1111any lcV IcM.H liies l1i.10
the cult ivatioln or (.ott.ol wvolill liavl' tO it' aInii diltii0ed lia\'iv"- g.n.rally
been given i pl). An especially li'fitana olei fea r'*.'ture of tine 1p'roblu0.,,L is
in the fact thaltt, tIwe weevil raihied l',Texas atLL what woi ild hav' l11u'en,
from othel r 4C isideratiolls, the, 111ost1 .,itiical tinm, in thn l istfl'y .1" fthe
)production oft thIle staple i tli' Statt'. 1The mal nlal fertilitv orf 11h
Cotton lands had been So gpeLat lat pulantiitterS lad itgl'ectedI copli.t()ly
such inatitent's as seed selectIion, varieties, fertilIizers, a1 irotta iion, t1 latt
must event ally receive consideration il l- any cotton-plUroitleing <'oincn-
try. In general, ,the only seed used was fromi tU"e crop of tlin, preced-
ing year, unselected and of absolutely unknown va'riety,m ILd th< ii;.
of fortiliwzers hiad not 1een practiced( at all. AllthlougiL it 1is ly 3'n
means tiue thatt t.he fertility of the soil liad b een exLhasted, nevc'rt lie-
less, on ilany of the older plantations in Texas the contin1111011 Is plant.-
ing of cotton within a run-down condition of the seed combined tol make
a change necessary in order to continue the industry profitilably.
A careful examination of the statistics, to which ]mor'e complete( ref-
erence is made in Farmers' Bulletin No. 181', has indicated that the
pest causes a reduction in production for a few years after its advent.
of about 50 per cent, but at the same time it is evident that most
planters within a few years are able to adopt the changes in tlhe sys-
tem of cultivating this staple that are made necessary iby the weevil,
so that the damage after a short time does not compare with that at
the beginning. Upon the foregoing basis, during the season of 1903
the weevil caused Texas cotton planters a loss of about $15,000),0(0(,
and this estimate agrees rather well with estimates made in other
ways by the more conservative cotton statisticians. A similar esti-
mate made in 1902 led to the conclusion that the damage amounted
to about *10,000,000. It consequently appears that during the years
the pest has been in Texas the aggregate damage would reach at least
$50,000,000. Many conditions of climate and plantatiolt practice in
the eastern portion of the cotton belt indicate that the weevil prob-
lem will eventually be as serious cast of thle Mississippi as it now is
in Texas. According to the estimates of Mr. Richard H. Edtmunds,
the editor of Manufacturers' Record, the normal cotton crop of the
United States represents a value of -*500,00U,()00, tihe extreme ulti-
mate damage that tlhe pest might accomplish over the entire belt
would be in thlie neighborhood of $250,(00,0()0 annually, provided none
of the means of avoiding dainmage that are now coming into common
use in Texas were adopted. In spite of the general serious outlook,
however, it must be stated that fears of the damage the weevil may
do are very often much exaggerated, especially in newly invaded
regions. It is not at all necessary to abandon cotton. The work of the
Division of Entomology for several seasons has demonstrated that a
crop can be grown profitably in spite of the boll weevil, and this expe-
rience is duplicated by many planters in Texas.






16
TERRITORY AFFECTED.

At the present time the boll weevil has not been found in the
United States outside of Texas (see fig. 1) except in three instances
in Louisiana. In one of these cases, at the sugar experiment station
at Audubon Park, in the vicinity of New Orleans, the circumstances
have led the State authorities to the conclusion that the pests were
purposely placed in the fields. The other two cases are isolated oc-
currences in Sabine Parish, in the extreme western part of the State.
Both of these are apparently traceable to importation from tlhe oppo-
site county in Texas, in cotton seed used for planting purposes or
possibly in hay. The authorities totally destroyed the cotton grow-
ing at the experiment station at Audubon Park, La., as soon as the
presence of the weevils was discovered. As no cotton is grown
within 9 miles of that point, it seems altogether likely that the colony
may have been completely exterminated. Similar action is being
taken regarding the two colonies found in Sabine Parish.
In Texas the infested area extends from Brownsville, where the
weevil originally entered the State, to Sherman. Shelby and Morris
counties represent the extreme eastern range. The cotton acreage
involved in this territory includes about 30 per cent of the cotton
acreage of thlie United States, which produced in 1900 about 35 per
cent of the total crop of this country, or about one-fourth of the crop
of the world for that year. There is, however, a considerable belt
between about the latitude of Dallas and the Red River where the
pest does not occur in uniform numbers in all cotton fields, and con-
sequently the general damage has not been great. It may be a matter
of only two or three years before it will become sufficiently numerous
to cut down the total production.
There are some features of special interest in the situation in Cuba.
Although the weevil has long been known to occur in the island, it
has attracted very little attention on account of the fact that the cul-
tivation of cotton was abandoned for a long time in favorof crops that
have been more profitable. Now, however, with the better price of the
staple and rather unsatisfactory returns from some other crops, cot-
ton is being planted upon a considerable scale. Mr. E. A. Schwarz
was sent to the island on two occasions to study the conditions there.
Although his report refers especially to the Province of Santa Clara,
it is probably true that conditions similar to those he describes obtain
everywhere. HIe found that the entire province is naturally more or
less infested by the boll weevil, and that weevils did not spread from
cultivated cotton planted with seed obtained in the United States to
the wild plants, as at first supposed, but from the latter to the former.
The weevils were found to be more numerous on the kidney cotton
growing wild than on the loose cotton (seminiella). The latter, when
growing alone, was usually found to be free from weevils, but liable
to be infested when growing in the vicinity of kidney cotton. A large






17











WILBARCHT

kw BAYLOR ARCHER CI.AY Ma~ ON gC & eLAMARRIE
1,,,RAYSO.RIVE BOWIE
II ,1 CABS -TVL







SHA EISO-%




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BUNTRMAVI
LLAHA A A HOO OS EI S
--- N^ rV-s

.c^ '^nn G\ U _.., F- O_^r F"ME XICO





RT -ENERI
PA VARRSKANLA
MASO M I AA M. WALKER


C1ORY-- ELL 5--0 1 r. L
-E#1 vH AR R TT Af
MON AS. 0ISLL 1N HN MF A 5SGEIN

MASND ER.t BrIIROOE M I a MAD ITY
A9ILLTTP IN RTAR~MS DALA L^^."-^ AA _f\ j




M LEPIN A TRVI LEE HARDIN



LI BER GRAN
1(U4 'tOMA i^ MOW. AY^ -r HRRS




I \* L ER J j fSOI-A


LAORTL BEE U3
MEDINALM L1 UOLAVACA |
WHSTR lBR







FIG. J- M ap sh w n a e nf s e y e i an c t on b l ee i re r w .
J'RIO ATAS4COSKARNE ^ HATAGORDA

LA SALLE IS \ ^REpu0^^ ^


ECNLDUVALI^ NUECES S UL P FP M XIO

ZAP ^A KrAt ill I





FIG. 1.-Map showing area infested by Mexican cotton boll weevil (redrawn.)
21739-No. 45-04--2






18

number of wild cotton trees growing in the vicinity of dwellings or
growing entirely wild are always infested, and here the weevils are
more numerous, but never as numerous as on the cultivated Egyptian
cotton. At one locality, where a large number of kidney cotton trees .
were growing (about 50 plants, some of them probably 20 years old),
it was found that at least one out of every twenty squares had been
punctured by the first week in March. From Mr. Schwarz's report
it. does not seem that there is a very promising outlook for cotton
raising in Cuba. The presence of wild perennial cotton, upon which
the weevil probably exists everywhere, will always be a source of
(d;mlIger. The long moist seasons and mild winters will form more
favorable conditions for the pest than will occur anywhere in the
United States.
PROSPECTS.
The investigations of the life history of the weevil that are referred
to in detail in the following pages have indicated that the most im- '
porliant elements in limiting the spread of an insect-namely, win-
ter temperatures and parasites-in this case offer no assurance that
thie pest will soon be checked. For the past ten years, except where
local unfavorable conditions have interfered, it has advanced annu-
ally a distance of about 50 miles. The insect is undoubtedly chang-
ing its habits and adapting itself to climatic conditions in new regions
that it is invading. It is undoubtedly true that it has acquired an
ability to withstand more severe frosts than occurred in the vicinity
of San Antonio in 1895. Except in a few particular regions, however,
it does not seem that the continued spread will be as rapid as it has
been. The country between Gonzales County and the Red River is
practically a continuous cotton field, and the prevailing winds have
undoubtedly favored the northward spread of the insect. Similar
conditions will now favor a rapid extension into the Red River valley
in Louisiana, and likewise there seems no doubt that the spread'will
be rapid in the Yazoo valley in Mississippi; but in most other situa-
tions throughout the belt the cotton fields are smaller and more iso-
lated than is the case in Texas; consequently it is to be supposed
that the spread of the pest will be retarded somewhat.
Basing estimates on a careful study of the distance the boll weevil
has traveled each year, as well as upon some attention that has been
paid to the means whereby it reaches new territory, referred to more
in detail hereafter (p. 94), it seems safe to predict that in from fifteen
to eighteen years the pest will be found throughout the cotton belt.
During the time it has been in Texas there has been no tendency
toward dying oet, and in south Texas the pest is practically as trou-
blesoine, except in so far as it is affected by changes in managing the
crop, as it was in 1895. In Mexico, where it has existed for a. much
longer period, it is apparently as plentiful as ever. Careful attention
that has been paid to the study of parasites and diseases, as well as






19


telmipetrattrures uiifiLvoLrablet) t h t ih e0 ii ct, ,.t, II.s filli'ih ( I1, reveal any p1o').1=-
pe't that it will (v'v li ,e ItInu'Ii less t1roItlesonet tha, nITW. ''Ti(e!1ro
will, ne(,e'ltheless, l seaLSonis fr(1m1 time t0tito HMii in whiCh i, 4 .i- dalIJage(
will be nuich l less tslan i()Inormal. ('lilmalti c conditions will inuni(lulllt.edly
causI tt'ieiIpolrary (1dil1inlt.i(o of u tIe litm121111 ,rs of,1 t.l he pest, in (vertaini
localities. In lexas tliese COll(liti()ls ham'e gin 'll 'iSep alIo1)st. (,(ry
year to tthe sui)ipositiLon on tlhe part of thei planiters tlint thl(e iis etts
have( di(,ed out. rl1is was .S1)ecially thi cas( i th(' region l)bLtwn(,1
Sailn Antonio and ( leeville in 19)()), and i( thI vic.inity 3of ('orpius
Christi in I):03. Both these years followed a series of seasons in
which there was in(,ch less than the normal rainfall; coilseq(lently not
only had a great many of the weevils been killed, bint the iiumel)rs
had been diminished by reason of the very limited extent to which it
was possible to raise cotton. IBoth 100() and 1903, however, were
exceedingly favorable for cotton. Early planting was possible and
there was an abundance of rain throughout the season. TIhe( crop
was so far advanced by the time the weevils became numerous tiat a
very fair yield was made, although in neither of the cases was any
top crop whatever produced. Whenever a series of years of scanty
rainfall is followed by one of normal precipitation the weevil will
temporarily be comparatively unimportant. The most disastrous
seasons will be those in which the rainfall is excessive and planting
unavoidably thrown late.
In this connection it becomes of some interest to speculate as to the
possibility that the weevil may event-ually be carried outside of the
United States and gain a foothold in other cotton-producing countries.
The fact that the insect is rather rapidly adapting itself to conditions
in the United States that are quite diverse from those of its native home
leads to the supposition that it would experience but little difficulty in
adapting itself to climatic conditions wherever cotton may be grown.
This probability of the spread of the weevil outside of the United
States is increased by the fact that cotton seed for planting l)iurposes
is frequently shipped from the United States to various parts of the
globe, and that within the last few years various conditions have
caused especial interest to be displayed in this matter. There is
nothing whatever to prevent weevils that may happen to be sacked
with cotton seed from being carried long distances on shipboard. In
the semidormant condition in which they hibernate they have often
been known to go longer without food than is ordinarily required for
a freight shipment from Galveston to Cape Town. Although there
are no truly cosmopolitan cotton insects, it seems likely that the boll
weevil may eventually be more widely distributed than any other.






20


LIFE HISTORY. 3
SUMMARY. I
The egg is deposited by the female weevil in a cavity formed by eat-
ing into a square or boll. The egg hatches in a few days and the
footless grub begins to feed, making a larger place for itself as it
grows. During the course of its growth the larva sheds its skin at II
least three times, the third molt being at the formation of the pupa,
which after a few days sheds its skin, whereupon the transformation "i
becomes completed. These immature stages require on the average
between two and three weeks. A further period of feeding equal to
about one-third of the preceding developmental period is required to
perfect sexual maturity so that reproduction may begin.
Variation in size depends directly upon abundance and condition
of the food supply. Weevils of average size are about 8 mm. in length,
one-third as broad as long, and weigh about one-fourth of a grain.
Color varies as widely as does size. It is usually of a gray or yellow-
brown, and is most markedly yellow in the largest weevils. Sexes
are produced in practically equal numbers, the males predominating
slightly. No other food has been found which will attract weevils
from squares and no plant but cotton upon which they can sustain
themselves for any considerable length of time. See Pl. II, fig. 12.

THE EGG. '
The egg of the boll weevil is an unfamiliar object even to many i
who are thoroughly familiar with the succeeding stages of the insect.
If laid upon the exterior of either square or boll it would be fairly
conspicuous on account of its pearly white color. Measurements
show that it is on the average about 0.8 mm. long by 0.5 mm. wide.
Its form is regularly elliptical (Pl. III, fig. 14), but both form and
size vary somewhat. Some eggs are considerably longer and more
slender than the average, while others are ovoid in shape. The shape
may be influenced by varying conditions of pressure in deposition
and the shape of the cavity in which it is placed. The soft and deli-
cate membrane forming the outer covering of the egg shows no notice-
able markings, but is quite tough and allows a considerable change
in form. Were the eggs deposited externally they would doubtless
prove attractive to some egg parasite as well as to many predatory
insect enemies. Furthermore, the density of the membranes would
Sbe insufficient to protect the egg from rapid drying or the effects of i
sudden changes in temperature. All these dangers the weevil avoids
by placing the eggs deeply within the tissue of the squares or bolls
upon which she feeds. As a rule, the cavities which receive eggs
are especially prepared therefore and not primarily for obtaining food.
Buried among the immature anthers of a square or on the inner side of
one carpel of a boll, as they usually are, weevil eggs become very incon-
spicuous objects (PI. I, fig. 3) and are found only after careful search.



*" "s i ;i ii.' i









EMBRYONIC IDEVELO()PMENT.

Owing to tii* t.ranspalrenc'y of .ite ngg iii'anl e't's, s(oietlling of
the development (of the ell'Vbryp) ean l seItn trirougli tlitii, l ill1 o
special study tas. yet beeien made ulp)Ol the sul.ject "of .te ('(r14yology
of the weevil. The fully dev(vlopIId ebry comi)hljt413,ly tills th1, inlt-
rior of the egg, its largo head being iin ol e (hl,(,- andL its 1 lod,' 'vlledW'1l
centrally upon itself till nearly double. Considerable motion is mani-
fested if the egg be touched at this periold.

LENGTH OF EGG STAGE.

Concealed as the eggs are beneath several layers of vegetable tis-
sue, it is impossible to examine them to ascertain the exact length of
the egg stage without in some degree interfering with the naturalness
of the accompanying conditions. The beginning of the stage was
easily obtained by confining female weevils with uninfested squares.
Careful dissections were then made of the squares at a little later
than what was found to be the average embryonic period at that sea-
son. In this way it is believed the range of error was reduced to a
fraction of a day in most cases, and a large number of observations
were made to still further reduce the error.
As shown by Table I, 553 observations have been recorded upon
this point, the majority of the observations being made in the fall of
1902. Considering the temperatures prevailing at the four periods
studied, it appears that the range in development during the average
season at Victoria, Tex., has been included, and it seems probable
that from these temperatures as a basis the length of the egg stage
can be approximately determined for any season and for any locality
within the present area of infestation.

TABLE I.-Length of egg stage t certain periods.

NumberA Mean Average Average
Numbertempera- efe'i''length of
Period of examination, ofobser- ture for tempera-. egg(
rations. tr o epr- g
atons period, ture.," stage.

1 02. 0F. F. Dhays.
September 4-October 3...................................-------------------------- 385 81 38 2.5 to 3
October 7-November 13 ......................... ........ 1l7 73 :1 4 to 4.5
November 27-December 1i5 ............................... 36 2 19 11
1903.
May 27-June5............................................---------------------------------------. 72.5 .32.5 3.5 to 4
Total ......................................------------------------------ .. ........ 3.4 to 4.1

"In considering the influence of temperature upon the weevils it has been assumed that. as has
been found to be the case with other animals, 43 F. would be about the lowest temperature at
which the weevils would be active. Temperatures blow that point would have, therefore, no
influence upon their activity, while all above that point would. For this reason it is better to
speak of the "effective temperature," meaning by that the number of degrees above 430 F.
Experiments made upon the influence of temperature upon the activity of weevils indicate
that this is very near the correct figure for this insect.
b Weighted average.

The extreme range observed in Table II in the length of this stage
is from two to fifteen days, while thle average period for the whole






22


number of observations is but three and six-tenths days. It is possi-
ble that the embryo can undergo an even greater retardation without
losing its vitality.
It may be noted here that drying of the square will also retard
embryonic development, but this condition does not occur in the field.

TABLE II.-Range in length of egg stage.

Number Length of Number Length of
of eggs. egg stage, of eggs. egg stage.
Days. Days.
2 2 4 5to 6
132 2to3 3 8 to 9
S 3 5 10 to 11
1"2 2 to 4 15 10 to 12
42 3to4 4 10 to 13
4 3 13 to 14
6 3 to 5 2 13 to 15
40 4 to 5
13 { 5
13 4 to 6


The length of the egg stage in bolls does not appear to differ greatly
from that in squares.
HATCHING.

While still within the egg the larva can be seen to work its mandi-
bles vigorously, and although a larva has never been seen in the act
of making the rupture which allows it to escape from the egg, it is
believed that the rupture is first started by the mandibles. The
larva do not seem to eat the membranes from which they have
escaped, but owing to the extreme delicacy of the skin it is almost
impossible to find any trace of it after the larva has left it and begun
feeding on the square.
I
HATCHING OF EGGS LAID EXTERNALLY.
It occasionally happens that females are unable to force an egg into
the puncture prepared to receive it and the egg is left on the outside
of the square or boll. Eggs so placed usually shrivel and dry up in a
short time. To test the possibility of a larva making its way into a
square from the outside, a number were protected from drying. Of
the 19 eggs tested, 6 hatched in from two to three days. In no case,
however, was the young larva able to make its way into the square
and it soon perished. The hatching of eggs laid externally is of no
importance, since the larve must perish without doing any damage.

EATING OF EGGS DEPOSITED OUTSIDE.

The number of eggs left outside increases as the female becomes
weakened, and is especially noticeable shortly before her death. The
number of such eggs which may be found is greatly diminished bythe
following peculiar habit, which was observed many times. Occasion-
ally it appeared that the puncture which the female had made for the
reception of an egg was too narrow to receive it, and after a prolonged
attempt to force it down the female would withdraw her ovipositor,






)3


leaving g the eg ,g at I the s, faIC'. ShitWM t 1hi Illt1 in1 llIIIieI'dli;Itlci%\ ;iI1
deh o'4)lr tie e ., A l Ite l at sIillin1 o(nI.sci ou 141 ltls )1 Ie" l [il -1. ;t11 l
aILw ,e 1 Of HIVte' 'a se, (ft it, shllIe ,v()O l pr d 1I ''(c d 10o lild ;idl 4.I ar ,.si e-
whatlit.le' avity l)peV'i(ouIsiy -imlde'. \ hNtI, I I is w s omp1111101i1t1.E slInwould
attep111 10 1o pla)1cP( aInthIe'r e'gg tlhetin. Ih(1 e ski second ;Il Iu.Tf u %t w;Is uIslu-
ally s uc.cessi'ul, 13utl i, in1 ole o tw(O (.s;lS S a f'eI. a Il. was si, t 1 fa1 il s4v ,i-ral
tinIes, aII d(1 il i or t l' al t le heIt IsfIfi r 4 I ,('IESs slMi- aIeV tlie .ggs, r s li as
been described.
IPERCENTA(E OF E(;(F S TIIAT HATCH.

Definite records were (not1 kept li1poI I Iis po )int, 1)111, il i1lo iany'
hundred(ls of eggs followed duri (lig these ol)s(,l'VLt ios very few f;iile.d
to hatch, 1thoglt (1sohle were re I lli Islower il emlb)vryoi, 1develop'I)me't,
than were others laid at tihe same time and by the satlie fIeiaIle. It
is the writers' general impression 1ta less tha 1 per (.vnttof tlhe eggs5
are infertile or fail to hatch.

THE LARVA.

DESCRIPTI( )N.
The young larva, upon hatching from the egg, is a delicate, white
legless grub of about 1 mnm. ( inchl) in length. Except for the
brown head and dark-brown mandibles, the young larva is at first as
inconspicuous as the egg from whlicli it cane. As it feeds and grows
it continues to enlarge a place for itself in the square or bolt until
the food supply has become exhausted or the vegetable tissues
are so chlianged as to be unsuitable for food. Iy this time, as a rule,
the interior of the square has been almost entirely consumed and the
larval castings are spread thickly over the walls of the cavity (PI.
III, fig. 15). This layer 1)ecomes firmly compacted by the frequent
turning of the larva as it nears the end of this stage. In 1 lie cell
thus formed occur the great changes from thle legless grub to tlihe fully
formed and perfect beetle (P1. I, figs. 7, 8, and 9).
Throughout this stage the body of the larva preserves a ventrally
curved crescentic form (PI. III, fig. 1;). Tlie color is while, modi-
fled somewhat by the dark color of the 1)(ody contents, which show
through the thinner, almost transparent, portions of the body wall.
The dorsum is strongly wrinkled or corrugated, whliile the venter is
quite smooth. The ridges on thlie dorsutnm appear t 1be formed largely
of fat tissue. After becoming full-grown tihe larva ceases to feed,
the alimentary canal becomes emptied, and both the color and form
of the larva are slightly changed. TIlie dark color disappears from
the interior and is replaced by a creamy tint from the transforming
tissues within. Thle ventral area becomes flattened, and the general
curve of the body is less marked. Swellings may bo seen onI tlhe sides
of the thIoracic region, and when these are very noticeable pupation
will soon take place.






24

GROWTH.

It is impossible to follow the growth of an individual larva with-
out interfering so greatly with its normal conditions of life as to
make the observations unreliable. It seemed m6re accurate to meas-
ure larvam of approximately known ages. In these measurements the
natural curve of the body was not interfered with, but the measure- i
ment taken across the tips of the body. In this way it was found |
that in squares during the hot weather the length of the body
increases quite regularly by about 1 mm. a day. As it becomes i
cooler the daily growth is less. In bolls which grow to maturity the
rate of growth is less and the length of the growing period is much
greater. Full-grown larvm vary in length from 5 to 10 mm. across i
the tips of the curve. Larvae of normal size in squares average from '
6 to 7 mm. The largest larvae are developed in bolls which grow to :
maturity (PI. III, fig. 19).
MOLTS..

To accommodate the rapid growth of the larva two or three molts
occur. The period of change from one instar or stage to the next is
so short that the chances of opening a square at just the right time
to observe the process are very small indeed. However, it has been :
ascertained beyond question that two molts occur before the larva j
reaches half its growth. The first occurs at about the second day i
and the second at about the fourth day. Whether a third molt ;
occurs before pupation can not be positively stated; but having occa-
sionally found larvae which had certainly just molted, but which were t
much larger than the usual size at the second molt, the writer is led l
to suspect that three larval molts may sometimes, though possibly ;i
they do not always, occur. In bolls where the length of the larval
stage is often three or four times as great as that usually passed in
squares it seems almost certain that more than two larval molts occur
regularly. Counting only the first two molts which have been often
found, a third occurs at the time the larva pupates.
p
PROCESS OF MOLTING.

So little is known in regard to the molting of Curculionide that the :
process as observed is here recorded. In the cases observed, starting
at the neck, the skin split along the back, and was then pushed down-
ward and backward along the venter of the larva. The cast head :
shield remained attached to the rest of the skin.
Immediately after casting the skin the head, as well as the rest of
the body of the larva, was of a pearly-white color. The tips of the :
mandibles first became brown, and within a short time a yellowish-
brown color marked the entire integument of the head.






j:....:: .











; t-- s-




11 ". t" .* r i " " "^ '''* ,i |1, ; f ,
L> '. 'r ~.. IA *"
Y/ // /, J// "/ / J" j-. / '/. /,' J\ o ." ,. ',

1" ,i,[ ffr / ./ ..
C. '1 / / /' ('/
'# .- / ' ". /', -,
L ,' ,* .* !' ***"*.. ." f .Aj /. "* " Jl fi *
^ -I; .^t .t ..... '~tl~ ..~i 11' ""


t



-f i
,#,___,,_-.




I


(ORIGINAL.)


FIG. 12.-COLLECTION SHOWING LIFE HISTORY AND WORK OF BOLL WEEVIL.



























ow








.,. U, *. I-- I-' Of A,


PLLAI III.


DEVELOPMENTAL STAGES AND WORK OF THE BOLL WEEVIL.
FPi. 13, Twn boll weevils fe.OdiriL on a square, natural size; fi-. 14, ,,-. i- ,l;t.l. '25 times natural
size: fig. 15, full-r,,-own lairvii in square, natural size; 1.6, ti. full-grown larva i-,litod,. natural
size: fig. 17, piu|. twice natural s.iz: fig. ls. adult just ian-nf, rmd. natural siz.: rith. 19. large
larvae in large boll,. two-thirds natural size; fig.2u. pupal cell in boll, broken olpe'n. twice natural
size. (Originial.)


B 4 ", o' f t .. .













M ost ()I ti h e' ,i, ,ini ,,p r l i.r,,il ,,tJSPI, wer,, lilt- l w,.,
Septem ler 1 I i(,,eI,'n ,. r .,, I',,i o1I 1,. um i.i yiin.'ii Ili 1 iiiiuS t l r-
ing thile first Ihal( la l, ,t. i ii.1;,iii. Il lI I t, i,,i r linarily I xi" r1 a, ,tn ,,W
at V ictoria djnrie L.. Iiih.ii ln l ii,. ; O, I l -, (3rt .ie ilrl Ix r E-'1m it f 1In4.




r average season may 'I' liii I ilij a bee n liii'.
The tiioe o( ),e,..i in .si it i,,n \. is easily 4'ter'mined by orx i,.ins itnigr
tested sqlia 're's i lr1-4-
  • of hatching r" tlit l;itrv' ,miliL un ly I),. rif', ml Iy Ji(hl iiitv IIi. siCli 'm.,
    and it was sfo .il I1(1 fWV t le \\aI 1 '11 ges agrees 1 yin %:.l" witIi pliici
    ill a s n gall icavilv f h i, mat, 1% lil'lili o tll iig ('UriE < ll ii'r, 1 fi it fri. N llv
    picked square lallfl sta'ig l.. w 11llr o1 tw' l) Of t e' t illin.tlll['1 Ztllfi r-.
    The coveeri g w t2li6i rl.sleratol W A r'earIf1lly a.S) 1)11s Iiglt.. Ai i Itl*.r
    disturbanee, was iie',,sary to ,letirin'1niin, ,xa l .ly 11% <.l;t*,0 Of pupaII-
    tion. ()bser'majtitns 1n1,144 io this wae v wns aIy 'ikn(,l i)n cltde-rs ntsinhe
    larva whieli wern- allhuvoil tho may f hien -i)e, C(IlpSitil to inp11a io
    under natural (mo (litiours all( l without, listi. ltbalil' l b until Ifi ml- (,f
    the la'al stai was approximately nrachedl. S.in.et, 11 4)in of tfll
    times fou sl for t:e various stas a1res r'ljlrxijttXly wil1 tl-
    known lnTLth of t.e immature e period il tass wtlo-lcn 14 nLo listill,'ji ure ii
    of normal conditions ocecUrl'rtd, we iimay ict(lude thiat 1i,( priodIs
    found for the larval stage were approximately Avrreet.
    Altogether 266 observations were reeord(d tempo ttem leigotl orf I ni.s
    stage. The majority of the observations may bl incue.dl ion tstage
    groups, and when thus grouped they maybe best considered i1n r9latin
    to the effective temperature. Table III presents a brief sauomaryl of
    these groups:

    TABLE III.-General results as to length o larval stage in squares.






    tempeatur remans aove 70 F.As tea temeratuefalbeo
    average fffct Numb aer Average
    Period of examination. tteaere reaeeiro of obser- m range of
    r iaturee nature. nations. stage.
    19M3. OF. F. Diys.
    September 6 to October 5 ---...-.....-.-...- .....--........ 7.7 3.7 195 6 to 9
    September 26 to October 21 -v.ath.-the.lngth.o.this.tagei s73.16 e. 6 15 7 to 12
    November 11 to December 12' --- -..-_--- "------ ----- ------ 62.5 19.5 15 20 to 311

    During the heat of summer the larval stage requires approximately
    one week. This time appears to hold so long as the mean average
    temperature remains above 75 F. As the temperature falls below
    that point there is a gradual increase in the length of this stage. The
    average total effective temperature required during hot weather by
    the larval stage is not far from 080 F. As development becomes
    retarded by colder weather the average total effective temperature
    required to complete it is much greater.
    These facts may be expressed in general by stating that during the
    hottest summer weather the length of this stage is somewhat less than






    26


    one week. Development becomes slower as the temperature falls, j
    but does not cease altogether so long as cotton can live. Even frosts i
    do not destroy larvae in the squares and bolls, and these may finish
    development during warmer weather after the frost has taken place.
    The length of the larval stage in bolls is as a rule much greater.
    If the boll falls when small the increase is slight, but if an infested
    boll grows on to maturity the larval stage more than any other is much
    extended. Special observations upon the larval stage in bolls have
    not been made, but reckoning from the known length of the whole
    developmental period in maturing bolls we may conclude that the i
    larval stage can not be less than six or seven weeks. :

    PUPAL CELLS IN BOLLS.
    As the boll approaches maturity, the full-grown larva ceases to feed
    upon the drying and hardening tissues of seed and fiber. Its excre-
    ment, more or less mixed with lint, becomes firmly compacted, and in
    the d(Iryiing which occurs the mass forms a cell of considerable firm-
    ness, within which pupation and the subsequent transformation to
    the adult, take place (Pl. III, fig. 20). These pupal cells frequently
    include a portion of the hull of a seed, but the writer has never found
    a large larva or a pupa entirely inclosed within a single cotton seed.
    The cells described are shorter and thicker than seeds, but in general
    appearance there is considerable resemblance between them (Pl. XI,
    fig. 44). -Doubtless these cells have misled some into the statement
    that they have found weevils in cotton seeds..

    PUPATION.
    The formation of the adult appendages has gone a good way before .
    the last larval skin is cast. The wing pads appear to be nearly half
    their ultimate size. The formation of the legs is also distinctly marked, :
    and the old head shield appears to be pushed down upon the ventral i::.
    side of the thorax by the gradual elongation of the forming proboscis. ;::
    Finally the tension becomes so great that the tightly stretched skin is
    ruptured over the vertex of the head, and it is then gradually cast off,
    revealing the delicate white pupa. The cast skin frequently remains
    for some time attached to the tip of the abdomen.

    THE PUPA.
    When this stage is first entered the insect is a very delicate object
    both in appearance and in reality. Its color is either pearly white
    or cream. The sheaths for the adult appendages are fully formed at
    the beginning of the stage and no subsequent changes are apparent
    except in color (P1. I, figs. 5 and 6). The eyes first become black,
    then the proboscis, elytra, and feumora become brownish and darker
    than the other parts (Pl. III, fig. 17).







    i 27

    Tle final i1olt. re14 1uires ail )ul t, flirty i iiillu1.s. 'lT'l skiin spjlits O|'nI
    over lhie frfnllit of tile li'adl aind sli (s dI wIIl Il, llg" li ],Vl0))S'i.s ;.n<|
    back over the prot.Iorax. The skin cli igs lto li.p anLtenl I;n;11141 1 tie lipl
    of theIO pr11)4)s'is till Ufler tlhe (l0rsuiL IIIas bl'eeii nli. nr'l atlll llI' &l'gs
    kicked free. 'I'lien Iy violently pullig ijOn llp m i skin willt IliI for
    legs first tihe tip of te li 0 snout1 andl llivin llhe ailelP ii,' 1ir. fri,4d, aind
    S finally tihe shrunken. and criumi'pled old skin is kicked olT t.Hi<, lip of
    Utl abdomen ly tihe ,Ii ind legs.
    LEN(T1[ OF PUPAL STA(;E.

    The length of this stage is mnore easily deternin inld Ilhan thai, of al3y
    other. It seemed .to make little dillerniie, il Ili tiLi(e whIlle,,r Jll,
    pupa' were allowed to remain in the Jsqtars or r'mov'd t(l)erefrom.
    Considerable variation in the length of this state L('xists aM1oiag inldi-
    S vidnals of the same generation and even between ofl'splring of t lie
    same female and from eggs laid on the same day. 'I'lhe, period( of
    investigation ranged from .uly to December, so that the extremes of
    the season are included. Altogether over 450 observations w(er lmadle
    upon the length of this stage. Nearly all of these are included in
    Table IV, which shows a summary of the results.

    TABLE IV.--7uiublar (irrangeif nt of obserralims Mupon the' liing/t/i tf pipjil .s7art
    in squares.


    Period of examination.


    1902.
    July 6 to 31.---.-.....--.................. ...........
    September 15 to October 3 ........................
    September 24 to October 2S .......................
    November 2 to 13-- .. ...............--------------......
    Decem ber 2 to 29 ..................................


    onbe M -r Range in Aver.age Average Total
    Number ingh leng effective effective
    oflbength length
    v nations of pupal. of stage. tempera- tempera-
    aons tage. ture. ture.

    Days. Imy.. F. F.
    161 2 to .5 3.5 M). 67 1:tS.A
    81 3 to 7 5.2 36. 11' 1s7.5
    167 4 to x 6.0 31.1 :.Ii.1
    29 5 to 6 5-. (; 2L. 2 1 6i. 7
    4 10 to 16 1.5 I. .) 269.11


    It should lbe noted in connection with Table IV that the observa-
    tions made in November were during a period of rather warm weneather
    and that the temperature records, for that time are incomplete. It. is
    likely that the average effective temperature given for that period
    might be different were the records comI)lete.
    The average length of this period during hot weather is from three
    to four days, and the period increases as the cool fall weather
    approaches to a maximum of about fifteen days.
    A comparison of Tables I, III, and IV shows that 11the decrease in
    temperature affects each stage in very nearly the same proportiolin.
    In each case the maximum recorded length of any stage is about four
    times its minimum, and the great retardation in each case occurs
    somewhere between 60 and 70- F. of mean average temperature, or
    17 to 27 F. of effective temperature. Even greater retardation
    occurs during the winter season.






    28


    The length of the pupal stage in large bolls has not bee- deter- :
    mined. It appears to be longer than in squares, but it certainly can
    not occupy the same proportional part of the entire developmental
    period that it does in squares.

    EFFECT OF BURYING SQUARES UPON PUPATION AND THE ESCAPE OF i
    ADULTS.
    The experiments made upon this point were designed to ascertain :
    the value, if any, in the plowing under of squares as a means of i
    destroying the larvae and pupae infesting them. But few experiments i
    seemed necessary to demonstrate the futility of this operation alone
    as a means of controlling the weevil.
    Squares which were known to be infested with about half-grown B
    larv? were placed in glass jars and covered with several inches of ..
    quite dry and fairly well pulverized earth. When examination was
    made it was found that pupation had taken place norihally while the
    squares were buried under from 2 to 5 inches of dirt. In no ease
    was pupation prevented, though a few weevils did not leave the
    squares after having become adult. Altogether about 100 squares
    were thus buried, and from them over 75 weevils emerged.
    In a portion of the preceding tests careful examination was made
    to ascertain how far toward the surface the newly emerged weevils .
    had succeeded in getting before they perished. It should be noted
    that these weevils had never fed, and they would have, therefore, less
    strength and endurance than such fully hardened adults as might be
    buried in the ordinary processes of field cultivation. Furthermore,
    the soil used was of finer texture and more compactly settled than it
    would be in the field. Twenty-seven weevils were found in this exam-
    ination, their location varying from the bottom of the jar to their
    having escaped through 4 inches of soil. A weighted average shows,
    however, that each weevil had made its way upward through 2 inches
    of dirt. We may infer, therefore, that had these squares been buried
    under less than 2 inches of fairly well pulverized earth, as would be
    the case from field cultivation, but a small percentage of them would
    have failed to make their way out. As it was, fully three-fourths of
    those leaving the squares made their way out through more than 2 :
    inches of dirt.
    In 1896 Mr. C. L. Marlatt noted that "the weevils can escape from
    loose soil when buried to a depth of 3 inches, but when artificially :,
    embedded 8 inches in moist soil they are unable to extricate them- I
    selves, as shown by test experiment." Quite extensive experiments "
    are now being made at Victoria to test the ability of the fully fed
    adult weevils to escape after being buried at various depths and in soil
    containing various percentages of water. That the moisture content
    exerts a great influence upon the texture of the soil is especially
    noticeable in the black bottom lands of the Texas cotton belt. While



    I....I






    ?)


    the results of these ex)terinIe ltNiitx y |I'iI'nllishl r1,a.440%l1s t1*ir i'1"i1ngi 1ng ou4[1
    conclusions u poil this poilti, the pe'se llt ilic' iatio isi that ltar b,1'-
    ficial effect of thorotungh cultivation lies in thle direl.t iii flniwi,*< wlhiaell
    that practice.( exerts upon ltII sti'ady ad rapdl)id growth I, J111 t.0II .(t1,,
    thus favoring tihe protiduietion of isqua,.res, t.in' s'letinzg ,1' 1Iills, anid tiOw
    early maturity of th crop rather titan in ti (liret dlest ructt ion ,aol tI lle
    weevils by burying them either vlile ii tihe sq(un re s or after the',y liLhae
    become:, ad u It.
    THE ADULT.

    BEFORE EMERGENCE.
    Immediately after its transformation flli thel plil);i t.imle aIltilt is
    very light in color and comparatively soft and helpless. ''lle prolos-
    cis is darkest in color, being of a yellowish brown; the pronotiiliii,
    tibiir, and tips of the elytra come next in depth of coloring. rI'lhi ely-
    tra are pale yellowishl, as are also the femora. The mrinouth parts, claws,
    and the teeth upon the inner side of the fore femora are nearly black.
    The body is soft and the young adult is unable to travel (Ill. Iill,
    fig. 18), consequently this period is passed where pupl)ation oce'turs.
    Usually two or more days are required to attain thie inor mial coloring
    and the necessary degree of hardness to enable the adult to make its
    escape from the square or cell.

    EMERGENCE.

    The normal method of escape from squares and small bolls is by
    cutting with its mandibles a hole just the size of the weevil's body
    (PI. IV, fig. 21). In large bolls the escape of the weevil is greatly
    facilitated by the natural opening of the boll (Pl. IV', fig. 22). Often
    the pupal cell is broken open by the spreading of the carpels, and
    when this is the case the pupa, if it has not already transformed,
    becomes exposed to the attack of enemies or, what is probably a more
    serious menace, the danger of drying so as to seriously interfere with
    a successful transformation. If the cell remains unbroken the weevil
    always escapes by the path of least resistance, cutting its way through
    as in the case of a square (PI. IV, fig.. 26). The material removed
    does not appear to be eaten, but is rather cast aside and left within
    the cell as a mass of fine debris.

    CHANGES AFTER EMERGENCE.
    At the time of emergence the weevils are comparatively soft, and
    they do not attain their final degree of hardness for some time after
    they have begun to feed. If they never feed they never harden.
    The color of the chitin is of an orange tinge at the time the weevils
    leave the squares or bolls, but after exposure for some time it turns
    to a dark chocolate brown. The development of the hair-like scales
    is probably entirely checked by the drying of the chitin, but the






    30


    darkening of the ground color makes the scales more apparent, and
    thus gives thi impression of further development after emergence has
    taken place.
    SIZE OF WEEVILS.

    Size of boll weevils is an especially variable quantity, and, as usual,
    varies almost directly in proportion to the abundance of the larva] i
    food supply and the length of the period of larval development. The:
    extremes are so great that the smallest and largest weevils would be
    thought by one not thoroughly familiar with them to be of entirely
    different species. So far as dimensions may convey an idea of the
    size, we may say that the weevils range from 3 to 8 mm. ( to inch)
    in length, including the l)roboscis extended, and from 1 to 3 mm. (i
    to inch) in breadth at the middle of the body. (See Pl. I, fig. 1.)

    RELATION OF SIZE TO FOOD SUPPLY.

    The smallest weevils are developed from squares which were very
    small, and which, for some reason, either of plant condition or of .
    additional weevil injury, fell very soon after the egg was deposited.
    The supply of food was not only small, but, owing to the immaturity
    of the pollen sacs, its quality was also poor. Normally squares con-
    tinue to grow for a week or more after eggs are deposited in them, and
    such squares produce the weevils of average size and color.
    The largest weevils are produced in bolls which grow to maturity.
    In them the food supply is most abundant, and the period of larval
    development is several times as long as it is in squares. Possibly ,
    these differences in size may be better shown by a summary of i
    observations which were made upon the weight of adults.

    WEIGHT OF ADULTS.
    The weevils used in these experiments were bred to insure their
    coming from the proper source. After emergence they were fed for i
    some time to bring them up to their normal weight, .

    TABLE V.-Siu inary of weight of weevils. ;:

    Source of weevils. Number. Average
    weigh t.
    Grain.
    Bred from picked small squares....----------------------.................. ---... -----------------. 25 0.105 ;
    Bred from average fallen squares-----.. --------.. ---------..-----------..--------.. 68 .231 ;
    Bred from large bolls----------------................-...---...- -----...------....-------------------- 6 .268 :::
    T total ...-.-.-- .. ..- .. ... ...... .. . . ........ . .. . ..--. .-- --- --. ------ 1626 1 36.825
    Average weight per weevil, all sources --- -------------------- ------. ----------- 22

    It should be noted that these figures do not nearly represent the
    weight of the extremes in size, but they do indicate the difference in
    the average weevil of each class.






    .. ':






    831o



    Color is 'vry 'ofte lli va'riableh (.laLractIet, 1 -l in isects, a41,t tI4 l,. Ni ll
    weevil pret'sents cojIsidleralihle range ill Ihis risplnet. Wliatevu'r iniiln-
    encI'es tlit sizo ofl the larva a fl'ects dii rely tie size o if, te ai lt1 t aill it
    is noticeal)lt that weevils of. the $114sale size ar alsoE, as. a rl11l., (loSIMly
    alike in color. In general, thle smaller tle size1 of 1 l, w.evil ilt(
    darker brown, is its color; the lar'gestl weevils are liglt yellowish
    brown. Between theese two extremes are, t1he nIajorit.y f average-
    sized weevils, which aret either ()f a gray-brown or dark yellow-lroWll
    color. Weevils developing il large l )olls, havig an aILI)nllant food
    supply and a developmllent't.al period atve'raging lore ttan twice llat
    of weevils in squares, are larger in size and more yellowish in color
    than are those from squares.
    The principal reason for the variation in color lies in tle degree of
    development of the minute hair-like scales, which are 1,1uch more
    prominently developed in the large than ini the sniall specimnens,
    although the color of old specimens is often changed by thie rtlilbing
    off of the scales. The scales are yellow in color, while tie ground
    color of the chitin bearing them is a dark brown or reddish brown.
    When the scales are but slightly developed, as seems to be the case
    with small weevils produced from underfed larvw, the dark-brown
    ground color is predominant, while in the case of large weevils pro-
    duced from larva having abundant food and a long period of devel-
    opment the scales are largely produced and give the strong yellow
    tone to the color which is characteristic of them.
    The development of the scales appears to take place mostly after
    the adult weevil has become quite dark in color but before it becomes
    fully hardened. They seem, therefore, to be a sort of non-essential
    aftergrowth which depends upon the surplus food supply remaining
    after the development of the essential parts of the weevil structure.
    SIZE AND COLOR NOT INDICATIVE OF SEX.
    Eminent coleopterists have studied the boll weevil most carefully
    with the purpose of discovering some external character by which the
    sexes could be distinguished, but all have failed to find any reliable
    points of distinction. The writer therefore does not hesitate to own
    that he also has failed to find any reliable character for the distinc-
    tion of the sexes. Many persons have the idea that the small dark
    weevils are males and the larger and lighter-colored brownish-yellow
    weevils are females. This idea is a mistaken one. In general it is
    probably true that the males are slightly smaller than the females,
    but judging from determinations of the sex of many hundreds of
    weevils it may be stated positively that size and color are characters
    which are related to food supply and length of the period of develop-
    ment and are not indications of sex. The sexes seem to be about
    equally represented among the smallest as well as the largest weevils.




    ---- .............. -.....;w u y wu E q


    32

    Characters commonly used to separate the sexes in the family Cur-
    culionid-e are not distinctive in this species. As a rule the antenna
    are inserted nearer the tip of the snout in the male than in the female.
    This character is variable among boll weevils; and though a large
    number of accurate measurements might show that a slight difference
    generally exists, it is too inconspicuous a character to be of general
    use. With most species the top of the rostrum of the male is rougher
    than is that of the female. However it may be with other species,
    there is but little if any difference in this respect between the young
    adults of the boll weevil. As the individuals become older the greater
    activity of tie females serves to wear the roughness from the top of
    the rostrum, and thus gradually, as a result of different habits, this
    character becomes more distinctive. In less than half of the boll
    weevils, however, is this character sufficiently noticeable to separate
    the sexes. The terminal segment of the abdomen shows no external
    difference in either sex, although in many weevils important charac-
    ters are there found.

    PROPORTIONS OF THE SEXES.

    No reliable secondary sexual characters having as yet been discov-
    ered, the certain determination of sex therefore rests solely upon the
    primary characters, thus requiring a certain amount of dissection in
    each case. Such determinations have been made upon large numbers
    of weevils taken in the field and upon many bred in the laboratory at
    various seasons of the year. The results are briefly summarized in
    Table VI.
    TABLE VI.-Proportions of the sexes.

    Number Number
    of males, ofal

    Season of 1902, both bred and from field .---....-...-----..-------.-------...------------ 240 860
    Hibernated weevils, 12-3----------------------------------------------...................................................... 269 174
    First generation, 1903 --.----- --.... -- ---..........----------------..------------------ 43 32
    Bred weevils, 190 -..-----.----.. ----.....-.. --------------------------------------- 45 88
    Field weevils, midsummer, 1903----....----..-.......------.---------------- -----------.. 52 59
    Total ---....--...------......---- ... --------... ----------- ----------------------- 649 8


    From these 1,207 determinations it appears that males are somewhat
    more numerous than females, the percentage being nearly 54 of males
    to 46 of females. It is noticeable, however, that the only season at
    which a preponderance of males occurs is during late fall. If we
    exclude the figures for hibernated weevils for a moment, we find that
    the totals for the balance of the season are remarkably close for the
    two sexes, being 380 males and 384 females. It seems safe to say,
    therefore, that the sexes are practically equal in numbers except that
    more males than females seem to be found among hibernating weevils.
    It may be that the retardation of development due to approaching







    Bul 4i, I of C.u. I p ..


    P Atll IV.


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    I



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    A ~
    ~


    4.) ~
    9Jn
    .


    BREEDING JAR AND METHOD OF ESCAPE OF ADULTS FROM SQUARES AND BOLLS.
    Fih,. 21, Em'rgvnveo hole made by weevil in square, natural size; fig. 22, weevil e-c.apin- nor-
    mally frm n hoIll. two-thirds natural size: ti2. 2:. apparatus used in 1'rc.'liig weevil-. ,'r,-fiirth
    natural i/z': fig. 21. larva destroying the ovary and 1rv i.tin, tlhe llimo in large squares,
    natural size: fig. 25, leaf fed upon by weevils in cfiiiiiim mt. one-half natural size: fig. 26.
    mnerwenr,.- hole of weevil from boll which never open. two-thirds natural size. (Original.)










































































































    ftU








    B., 4", of r ., '.. U L, I '.. of -,


    FIG. 27.-LARVA IN SQUARE, OVARY UNTOUCHED, NATURAL SIZE. (ORIGINAL'.


    FIG. 28.-LARGE AND SMALL LARVAE IN BOLL, TWO-THIRDS NATURAL SIZE. (ORIGINAL.)




















































































    ; f




























    f"



    !'' .












    ^
    '' T11


















    I-

    ''I-






    33


    colti weather favors the ldevelo)imiett ofl males. NNot., ly iwas 1 li.re a
    larger number ofl males than of fe tal's take i in Dece),eri i 1', but
    there were also n mwoe males than females taken iln i lie ild in til 1. spring
    of 1903 ainong he l hibernated weevils whichll lived thlrought lhoe winter.
    Accordilltg Ito tht determinationLs made,, (14 per ent. of t, le 259 weevils
    dying during t1he 'winter were mahes an1i ,(1 5per cent (of I lie weevils liv-
    ing through t lie winter were also m]ales. Since it, appears tM htat females
    require fertilization in the spring bl)efore thlley lgin 1 ( ilIosit eggs,
    the prelponderanc otf males at tlat tim1t ai 'L(tS as It prov)1'ision Ito insure
    the p)ropagation of the i species.

    LEN(;TH OF LIFE UI'ON SQUARES.
    The observations made along this line 11113may e) divided ito eightt
    groups, each dealing with some special food condition or class of
    weevils. For the confinement of weevils in the laboratory the most
    satisfactory apparatus tried, both for convenience in handling and for
    the maintenance of favorable conditions for the weevil, was made up
    as follows: A 4 or 5 inch shallow earthen saucer, such as is used with
    flowerpots, was filled with soil, which was kept fairly moist. Over
    this was placed a fresh cotton leaf, which conserved the moisture from
    the soil, but never became wet, and kept both weevils and squares
    clean, besides facilitating the handling necessary to frequent renew-
    als of the food supply and the consequent transference of the weevils.
    The 'rest of the cage was formed by an ordinary lantern globe cov-
    ered at the top by cheese cloth held firmly in place by a rubber band.
    With this apparatus weevils could be readily observed without dis-
    turbing them, and food supplied was kept in good condition and could
    be easily renewed, while there were no cracks to hide in or to allow
    weevils to escape (P1. IV, fig. 23). The moisture of the soil and
    fresh leaf covers were renewed as needed. Clean squares were sup-
    plied each day, and the actual number of egg and feeding punctures
    recorded upon numbered slips kept with each cage. The sex of each
    weevil was also determined and noted upon its death, thus giving an
    accurate record of the number and sex of weevils responsible for the
    punctures recorded. Most of the weevils used were bred, so that tlhe
    exact length of their lives is known. Length of life refers only to
    adult life from the time of emergence from the square or boll to the
    death of thlie weevil. Many weevils brought in from the field were
    under observation in the laboratory for periods sufficiently long to
    justify the inclusion of the results obtained from them with those of
    weevils which were bred. Obviously the time these were under
    observation does not represent their true length of life; therefore the
    inclusion of both results renders the averages obtained the more con-
    servative.
    21739-No. 45-04--3






    34

    TABLE VII.-Length of life of weevils upon squares.

    Males. Females.
    Number. A ge Number. Average
    dNys. Number. days.

    Weevils placed in hibernation Dec. 15,1902; living Apr. 15,
    Hibernated weevils taken spring, 190; estimated aduiit 180 14 171
    Dec. 15, 1902---------------------------------------------------- 66 223 53 220
    Hibernated weevils, from time of feeding in 1903.- ----- 23 57 16 37
    I. 67 88 52 80
    First generation, bred --...--. ----... -------------------................. 30 58 25 56
    Third generation, bred.----------------------------I 18 43 10 54
    Fifth generation, bred -..-----------------------------I 9 76 9 54
    Totals and weighted averages, including hibernation
    period ........-- --------------------- -- ---- .--.---.- .... 146 151 111 148
    Totals and weighted averages, npt including hibernation
    period -- -------------------------- 147 71 112 64
    Entire length of life, hibernated weevils only ------------- 89 212 67 210

    Whether we include the time of hibernation or not, it appears from
    the averages of 156 hibernated weevils that those which winter suc-
    cessfully are longer lived than any following generation, as their
    active life in spring averaged fully 80 days for males and 70 for
    females. Probably the greater activity of the first generation may
    account for their somewhat shorter life. The average active life
    period for all generations is probably not far from 71 days for males
    and 64 days for females.

    LENGTH OF LIFE ON BOLLS ALONE.

    As weevils appear to feed freely on bolls in the field after the period
    of maximum infestation has been reached (P1. I, fig. 10), these tests
    were made to determine whether they might be able to live normally
    with no other food.
    A number of weevils were placed upon bolls as soon as they became
    adult. Others which had first been fed upon squares were given bolls
    after they had become hard and had shown themselves to be in a nor-
    mally healthy condition. Of the total 37 weevils thus tested, 16 were
    males and 21 were females. The males showed an average length of
    life of 19.7 days, while the females survived for only 15.2 days. This
    is a much shorter period than the normal length of life upon squares
    for either sex.

    LENGTH OF LIFE ON COTTON LEAVES ALONE.

    To determine whether they could live upon the foliage of cotton
    alone 69 newly transformed weevils were at the 1st of October, 1902,
    placed upon fresh leaves, which were renewed at frequent intervals.
    During the first three weeks 52 of these weevils (21 male and 31
    female) died, leaving 17 alive and well; 11 of these were then returned
    to squares and 6 continued upon the leaves. Of these 6, 3 lived to be
    81 days old and were then intentionally killed for dissection. The


    'I






    35

    average length of life of those kept entirely utipont hlaves was over 30
    days. These riesultfts show early the ability of inany of tin1 weevils
    to live uponl foliage alone in fields in which fall grazingli iS praetiif'I
    until it. becomes suiflieiently cold for them to go into winter q(jartA'rL
    (see PI. IV, fig. 25).

    LENGTH 0F' LIFE WITH SWEETENED WATER AND WITH MOLASSES.
    So 1much has been said about the attracltioll of molasses for lie
    weevils that tests were nlade with a cheap grade of Inolasses diluited
    with from 20 to 25 parts of water to see whether this soltiion really
    served them as food. The weevils used were just adult and li ad taken
    no other food. They fed quite readily upon the solution, remaining
    quietly with their snouts in the water for from a few minutes to an
    hour and a half at a time. The solution did not seem to draw them
    from any distance, l)ut as soon as a weevil came to it it would stop to
    drink. Feeding or drinking took place daily or oftener until the
    death of the weevils. The average length of life for the 12 weevils
    used was a little less than 6 days.
    As weevils without food but with water lived an average of 51
    days, the conclusion is that a solution of molasses 1 to water 25 parts
    does not serve the weevil as food, since it does not noticeably prolong
    life.
    Six weevils just emerged kept upon undiluted molasses showed a
    greater length of life, these dying at an average age of 11 days.

    LENGTH OF LIFE WITHOUT FOOD, BUT WITH WATER.
    These observations were made during August as a check upon those
    without water. The 8 weevils used were just adult and had never
    fed. Each weevil drank for one or two minutes at least once each
    day so long as it lived. All died at nearly the same time, having
    lived for an average of about 5! days. As those without water lived
    an average of 5 days, it appears that access to water in the absence
    of food does not materially increase the length of life of the starving
    weevils.
    LENGTH OF LIFE WITHOUT FOOD OR WATER.
    Three series of observations were made along this line. In the first
    the weevils used were taken immediately after emergence and never
    allowed to feed. Fifty weevils were tested in this way during July
    and August and showed an average length of life of 5 days from the
    date of emergence. A few lived as long as 8 or 9 days. These never
    acquired as dark a color nor as great a degree of hardness as is normal.
    In the second series the 15 weevils used were 7 weeks old and full-
    fed at the time of beginning the test. These showed an average length
    of life of slightly over 6 days, the range being from 5 to 9 days. These
    weevils were tested during the latter half of November, and the late-






    36

    ness of the season, together with the full-fed condition of the weevils,
    seemed to promise a considerably longer period than 6 days.
    In the third series the IS weevils used were 1 month old and full-
    fed at the beginning of the test in the middle of November. The con-
    ditions in this series were as in the series preceding, with the excep-
    tion that an abundance of two species of grass taken from cotton
    fields was included. These weevils showed an average length of life
    of nearly 7' days, ranging from 3 to 10 days. The weevils made no
    effort to feed upon the grass, so the slightly longer life period must
    be due to other causes.
    CANNIBALISM.
    It is hardly proper to speak of cannibalism as a food habit of the
    boll weevil, but the facts observed may well be recorded here. Under
    the impulse of extreme hunger weevils have several times showed a
    slight cannibalistic tendency.
    Seven beetles were confined in a pill box without food. On the
    third day 6 only were alive. Of the seventh only the hardest chitin-
    ized parts (head, proboscis, pronotum, legs, and elytra) remained, the
    softer parts having been eaten by the survivors.
    In another box containing 12 adults the leaf supplied for food was
    insufficient, and on the fourth day 8 were dead, 4 were partly eaten,
    and others had lost one or more legs each.
    In another case a few young adults and a number of squares con-
    taining pupw were placed in a box together with a few fresh squares
    to serve as food for the adults. When the box was opened after a
    number of days, one "reddish-brown" adult was found having its
    elytra eaten through and most of its abdomen devoured. In spite of
    this mutilation the victim was still alive and kicking slowly. The
    squares were still fresh and fit for food, so that this is really the clear-
    est case of cannibalism observed.
    Frequently more than one larva hatches in a square, and when this
    is the case a struggle between them is almost certain to take place
    before they become full grown. Many cases have been observed in
    which squares contained one living and one or more smaller dead
    larve, while in a few cases the actual death struggle was observed.

    HABITS.

    Among the habits of any insect of economic importance, the first
    for careful study are those relating to its food, and secondly those
    connected with its propagation. The study of the life history of the
    boll weevil has revealed no especially vulnerable point, but rather the
    important fact that in all its stages it is better protected against the
    attacks of enemies and the ordinarily effective remedies recommended
    by the economic entomologist than any other insect which has ever
    threatened the production of any of the great staple crops of this



    ::
    e iF
    "Ei : '" E "'






    37


    country. Naturally, theiI, we 1Illist iM-ds Ctirn iito IL s1 iIly of tl<, 1,aliits
    of the pest to poinilt t.l tl wiLv y <> lvi s 1 I1y whV ic'i Ch ,it1'er it. 1my lI iWiself
    destroyed or its great 1lestrtilctiveln-iss pIrev enteld.

    FOOD HABITS.
    LARVAL.
    It is plainly the intention of tihe mother weevil to deposit her egg so
    that the larva lupon hatching will find itself surroiIndedl Ly an abun-
    dance of favorable food. In the great 1mLjority (of eases this foofl con-
    sists principally of iimmiatture 1)llen. This is the first food of the larva
    which develops in a sqpiare, and it must, be Iboth delicate and nutritious.
    Often a larva will eat its way entirely around a square in its lpursuiit
    of this food. In most cases the larva is about lialfi grownl before it
    feeds to any extent, upon the other portions of the S(luare. It,1 may
    then take the pistil and the central portion of the ovary, scooping out
    a smoothly rounded cavity for the accommodation of its rapidly
    increasing bulk (P1. I, fig. 7; PI. III, fig. 15; 1lI. IV', fig. 24). So
    rapidly does thlie larva feed and grow that in rather less than a week
    it has devoured two or three times the bulk of its own body when fully
    grown. It sometimes happens that the square is large when the egg
    is deposited therein, and the bloom begins to open before the injury
    by the larva is sufficient to arrest its development. In many cases of
    this kind the larva works its way up into the corolla and falls with it,
    leaving the young boll quite untouched (PI. V, fig. 27). Occasionally
    the flower opens and fertilization is accomplished before any injury
    is done the pistil, and in rare cases a perfect boll results from a truly
    infested square. Sometimes the larva when small works its way down
    into the ovary before the bloom falls, and in such cases the boll falls
    as would a square.
    In large bolls the larvpe feed principally upon seed and to some extent
    upon immature fiber. A larva will usually destroy but one lock in a
    boll, though two are sometimes injured (P1. V, fig. 28).

    ADULT.
    Before escaping from the square tlhe adult empties its alimentary
    canal of the white material remaining therein after the transforma-
    tion. The material removed in making an exit from the cell is not
    used as food, but is cast aside. Weevils are ready to begin feeding
    very soon after they escape from the squares or bolls in which the
    previous stages have been passed. For several days thereafter both
    sexes feed almost continuously and seem to have no other purpose in
    life. They will take squares, bolls, or leaves, but they much prefer
    the squares, and when squares are present in the field it is probable
    that leaves are seldom touched. As has been shown, however, weevils
    can live for a long time upon leaves alone when squares anti bolls are




    :... E... .. ::... :


    38

    wanting. Bolls are only slightly attacked *so long as there is an
    abundance of clean squares.
    The method of feeding is alike in both sexes. The mouth-parts
    are very flexibly attached at the tip of the snout (fig. 2) and are
    capable of a wide range of movement. The head fits smoothly into
    the prothorax like the ball into a socket joint and is capable of a con-
    siderable angle of rotation. The proboscis itself is used as a lever in
    prying and helps to enlarge the puncture through the floral envelopes
    especially. Feeding is accomplished by a combination of movements.
    The sharply toothed mandibles serve to cut and tear, while the rota-
    tion of the head gives the cutting parts an auger-like action. The
    forelegs especially take a very firm hold upon the square and help
    to bring a strong pressure to bear upon the proboscis during certain
    portions of the excavating process. The outer layer of the square,
    the calyx of the flower, is naturally the toughest portion that they
    have to penetrate, and only enough is here
    L removed to admit the snout. After that is
    pierced the puncture proceeds quite rapidly,
    A combinations of chiseling, boring, and prying
    movements being used. While the material
    removed from the cavity is used for food, the
    bulk of the feeding is upon the tender, closely
    compacted, and highly nutritious anthers or
    pollen sacs of the square. When these are
    IIreached the cavity is enlarged, and as much is
    FiG. 2.-Mexican cotton boll eaten as the weevil can reach. The form of
    weevil, head showing ros- the entire puncture becomes finally like that
    trum with antenna near
    middle and mandibles of a miniature flask.
    at end-much enlarged Only after weevils have fed considerably do
    (original).
    sexual differences in feeding habits begin to
    appear (Pl. III, fig. 13), the females puncturing mainly the base and
    the males the tip of the square.
    Feeding punctures are much larger and deeper than are those made
    especially for the reception of the eggs (P1. I, fig. 3); more material
    is removed from the inside of the square or boll and the opening to
    the cavity is never intentionally closed. Feeding punctures are most
    frequently made through the thinner portion of the corolla not covered
    by the calyx. The exposed tissue around the cavity quickly dries
    and turns brown from the starting of decay. As a number of these i
    large cavities are often formed in one square (PI. VI, fig. 29), the
    injury becomes so great as to cause the square to flare immediately,
    often before the weevil has ceased to feed upon it. Squares so
    severely injured fall in a very short time. The injury caused by a
    single feeding puncture is often overcome by the square and its nor-
    mal course of development is continued. When feeding punctures
    are made in squares which are nearly ready to bloom, the injury corn-






    39


    only produclves. a distorted Ilhoo1n (Pl. V1, fig. :(3) JaLJd inl very s've,'r'
    Cases thi 1o)oll will dro'l sooJn after setltil g.
    After the females 1begi n to 0%'iposit, their feedl:lig haluits ie'oi'I
    quite different from those of timnI males. Ip to t his i tille, )othl sMxes
    mnov hlt lit. 1, iimaking a tinumbier of plihnctuisM ill a isinlghle sliiarte; butt
    from tl is point, we must consider the feeding habits of tIhe sexes sep)-
    arately.
    M.\%I ,K.
    Studie.s ofr the feedding habits of tiales hav been made both in the
    labl)oratory andl out of doors. In the laboratory ;5 males wer unmi(der
    observation during a total period of 2,4!92 weevil-days." 1)During this
    period 2,18.5 squares were supplied them and they made 5,617 feeding
    punctures in1 1,5-2 of these squares. A little calculation shows that they
    averaged to make 3A feeding punctures in each square, at the rate of 24
    punctures a weevil each day. These observations were in most cases
    made during the latter part of each weevil's life. During the first few
    days they have often been found to make from 6 to 9 punctures a day.
    A general average of 3 feeding punctures a day in the laboratory
    would seem to be near the actual figures during the warm weather.
    As each male while under observation attacked only about 2
    squares every 3 days, the destructiveness of males seems compara-
    tively slight.
    Five males were followed upon plants under a field cage for a total
    period of 145 weevil-days. During this period they attacked 68
    squares, making therein a total of 177 feeding punctures. This
    means an average of 2.6 punctures per square and an average of 1.2
    punctures per male per day, making the number of squares attacked
    by each male less than 1 every 2 days. These outdoor observations
    indicate that the laboratory results, small though they appear, are
    yet higher than the actual field numbers. Whether in or out of
    doors, the activity of feeding decreases as the male grows older.
    Males choose to puncture more often than do females through the
    tip portion of the square not covered by the calyx. The yellow or
    orange colored excrement is abundant, and owing to the somewhat
    sedentary habits of the males it accumulates often in quite large
    masses.
    FEMALE.
    After they begin to oviposit females seem generally to feed less
    upon one square or in one puncture than they do previous to that
    time. They obtain quite a considerable portion of their food from
    the excavations which they make for the deposition of their eggs, and
    as they show a strong inclination to oviposit only in clean or pre-
    viously uninfested squares, their wandering in search of such squares

    a The term "weevil-day'" is used for convenience to designate the product of
    the two factors; number of weevils multiplied by the number of days.







    40

    keeps their punctures scattered so long as plenty of clean squares can
    be found. When clean squares become scarce, the normal inclination
    can not be followed out, and the number of punctures made in one
    square will be greatly increased. Most of the special feeding punc-
    tures of females appear to be made either in the early morning or -
    near sundown, the middle and warmest portion of the day being
    given mainly to egg deposition. The total amount of feeding done is
    really very large, as is shown by a few figures.

    MALES AND FEMALES TOGETHER.

    During the season of 1903 a large number of weevils was kept in
    the laboratory for special study, but as several weevils were confined
    in each cage, the work of the sexes can not be positively separated.
    A comparison of the results can best be made by means of a tabular
    arrangement of the figures.

    TABLE VIII.-Number of punctures per weevil per (lay.

    Total. Average.
    Characterization of Number Number Feeding Egg
    lot. of males. of fe- Weevil Feeding Egg punc- punc- Period of
    males ys punc- punc- tures per tures per observa-
    days. tures. tures. weevil female tion.
    day. day.

    Hibernated weevils Days.
    in laboratory....... 5", 54 4,938 17,406 5,702 3.54-- 2.3+ 45.3+
    Hibernated females
    in field cage-------- ---------- 4 93 284 489 3.0+ 5.3- 23.3-
    Weevils of first gen-
    eration in labora-
    tory ..... ... 31 27 3,258 16,487 3,565 5.0+ 2.4- 56.2--
    Females, first gener-
    ation, in field cage --.. ---- 5 70 263 435 3.8- 6.2+ 14.0
    Males only, labora-
    tory, summer of
    1903----------------- 65 ---- 2,492 5,617 .---------- 2.3- ------- 38.3+
    Total ----------- 151 90 10,851 40,057 10,191---------- ------- ----------


    FEEDING OF HIBERNATED WEEVILS ON EARLY COTTON.

    During the period in which hibernated weevils were coining from
    their winter quarters and seeking their first food, frequent examina-
    tions were made in fields where the cotton was most advanced to learn
    the first-food habits of such weevils. From statements made by pre-
    vious investigators the writer is led to believe that the season of 1903
    at Victoria was abnormal in respect to the small number of hiber-
    nated weevils which were to be found upon the young cotton in the
    field. The most careful search failed to discover more than a very:i
    few weevils, whereas at the same season in some years hibernated .
    weevils have been picked in large numbers from the young cotton
    growing in the infested territory. ;;
    Whether they be few or many, however, makes no difference inii
    the feeding habits of the hibernated beetles. The stage of the cotton
    determines largely the nature of the food habits at this time. Owing


    -- i *









    to t 'w e(xlre e wet,,y wd winter island tite very late.lt spring of JI'i,1: little.
    cotton could I, ptlaintel Initil tIliII hitter aI't. o if iMarch ar W ir ie'fi r pasl art
    of Aip'il. I III I SulcL s LasonL as this, therefore, c, u. lti o iinlist IN" si. mall
    at th t tiee Li tllt if e el iergetnt' o l"if l wte'tvils 1`1 I' 1ull Ii-lllatiOll, a nW i
    Somettimle Inliist. elapse N 'fore tihi I'ormat i';oirnl IorI iI 'e lirsi Sq1Ilares' fulr-
    nishes liv weevils withl their niorinal I')oo s.ppl3y. I hiring this int1111,r-
    vail tint w\ee vil getls iao st, o its fto.d fr'ro lit, tender, ra lfly growing
    tPerilinal i)0rtioln of the .01o1uig jlatsI t, as se'ver'l o1sl.'erv'rs V uaS te otet,1]d.
    T'Ije central I)IId, young leaves, oP 1.1' Iie iiSltndr st' Ills aIe' atII'dtacked andl
    ulpon thieset the w,'wevils easily sub)sis1t nitil sqluarn's art develoiii'dl, iaftle
    which they confinll their injury to thei i.
    The earliest plants in a field seemI to attract, most of t IhI I, weevils,
    and where seppa" plants occur they serve as excel lent traps to draw
    the first attacks. 'Tllus, in the spring of 1895l Mr. E. A. Seliwarz found
    thle first emerged hi)erInated weevils working upon seppa plants which
    had sprung from 2-year-old roots. Thliese plants seen tin o start earlier
    and grow more vigorously than do those from seed and are therefore
    doubly tempting to the hungry weevils.
    In 1896 Mr. Marlatt noted "the eating in the field on volunteer cot-
    ton is practically confined to the young expanding leaves at the blud
    and to the tender petioles or stems of this portion of the plant."
    In the spring of 1903, in one field of comparatively early cotton, 2
    or 3 acres in extent, the writer found, between April 24 and May 11,
    23 weevils working on the buds and tender leaves of seppa plants
    before a single weevil was found upon the young planted cotton ha\-
    ing from 4 to 8 leaves.
    If, however, the cotton should be further advanced at thie time tihe
    weevils appear, ihey would then go at once to the squares. Even
    then they prefer to attack thle most advanced plants, which have a
    number of nearly grown squares, rather than the smaller plants which
    are but just beginning to square. Seppa plants, where such exist,
    come in, therefore, for a large part of the first attack of tihe hibernated
    weevils. This fact is well shown by observations made by Mr. A. N.
    Caudell, of the Division of Entomology, at Victoria, at about the
    middle of June, 1902. In an examination of 1(M) seppa plants growing
    in a planted field he found that fully half of the squares upon those
    plants were then infested. The planted cotton was just beginning to
    formn squares, and was but slightly injured at that time.

    INCREASE IN LEAF AREA OF COTTON.
    The advisability of making observations upon this point was sug-
    gested by the attempts made to poison hibernated weevils by spraying
    early cotton with an arsenical insecticide. As the weevils fed so

    a Seppa" is the term used by the Mexican residents of South Texas to differ-
    entiate the cotton plants springing from the roots of the previous year from those
    strictly '"volunteer." springing from accidentally scattered seeds.







    42

    exclusively in the most recently unfolded growing portions at the tips
    of the stems, it was evident that the rapidity of increase in the leaf
    area would at least indicate the frequency with which spraying would
    have to be repeated in order to keep in a poisoned condition the very
    limited portion upon which the weevils fed.
    Although the observations were made after midsummer, the plants
    used were of the right size to indicate the points desired. Two series,
    each including five average plants, were selected.
    The plants used in Series I had 8 leaves at the time of the first
    observation. Those used in Series II were older and averaged about
    30 leaves each. The leaves borne upon the main stem were classed
    as primary and those from side branches as secondary leaves. Upon
    the date of each of the 5 observations made, the number of leaves in
    each class was ascertained, an average leaf in each class was quite
    accurately measured, and the total product of numbers and area thus
    found was considered as the approximate leaf area of the plant. The
    error has been reduced as much as possible by taking an average of
    the 5 plants in each series as representing a typical plant, and it is
    with these results that comparisons have been made.
    TABLE IX.-Estimated increase in leaf area of cotton, averages of five plants.

    Primary leaves. Secondary leaves.
    Average Percent- Average Average Percent-
    Date of examination, number Average ve of number aea ae of
    pe a daily in- per art daily in-
    plant. plant crease, pFan t. plant, crease.

    1902.
    Series I: Sq. in. Sq. in.
    August30 --------------------------- 8.0 64.0 ------------ 0.0 ------ ------
    September 13---..-------..------------- 8.6 136.8 8.0 8.0 41.2 ----------
    September25------....-...-------.....---- 9.8 231.6 5.4 16.6 187.4 80.0
    October6.---------------------------- 11.0 309.6 3.0 22.6 347.8 7.8
    October 17..-----...----------------------- 13.2 376.6 2.0 31.0 522.4 4.6
    Series II:
    August30-------....--.---......--- ..----------- 7.8 177.2 ---------- 21.6 266.8 ----
    September 13 ----------------------- 8.4 229.2 2.0 24.8 341.4 2.0
    September 25----------------------- 9.8 241.6 .04 42.4 514.0 3.6
    October6.--..--------... ----------....-------- 9.6 214.8 a-1.0 52.6 619.2 1.8
    October 17.----..---..----....--.....-----------. 10.0 216.8 --------- 67.4 808.8 2.1

    a Decrease of I per cent due to falling of old primary leaves.

    Several facts are evident from an examination of this table. After
    the plant has acquired about eight primary leaves the formation of
    branches and of secondary leaves began, thereby multiplying the
    number of growing points. From this time on the greater part of the
    increase in leaf area took place in the secondary leaves. By far
    the most rapid period of leaf growth occurred at about the time when I
    squares first began to form. In Series I the average total leaf area
    practically doubled every ten days through the seven weeks under
    observation. In Series II the plants were older to start with, and it
    required about forty days to double the leaf area.
    Everyone now concedes that it is useless to attempt the spraying
    of full-grown cotton such as is represented in Series II. The extreme








    rapidity of increase in thei foliage' area shown it ll lth 11irst jLrt Of
    Series I shows Ithat spraying miust be repeat'ed ivery week or e1.i'n lays
    if even one-hialf of th entire leaf area is to Ie kept poi.soiid.. When
    in Connection with the large per cent. of daily increase wie .osider
    how much of that, percentage is b beingg unfolded at the very ilp of 0the
    stem; that upon that limited tip area alone will the weevil feel before
    the formation of squares; tlhiat after thlie formation of squlareis it
    appears to 0be al)soluteAly impossible to poisoll (I the weevil's food sup-
    ply, and also that tihe irregular emergence of the weevils from lhiber-
    nation may extend through several weeks, it at once becomes evident
    that spraying early cotton for hibernated weevils is almost as1 imprac-
    ticable as the spraying of older cotton is now acknowledged to be.

    EFFECTS OF FEEDING UPON SQUARES AND BOLLS.
    From numerous large, open, feeding punctures a sq(uaire becomes
    so severely injured that it flares very quickly, often within 24 hours.
    Males usually make the largest punctures, and always leave them open
    while they remain for a day or more working upon the same square.
    It has been often found that squares thus injured by a male will flare
    before the weevil leaves it. The time of flaring depends 1)upon the
    degree of injury relative to the size of the square. Thus, small squares
    receiving only a single large feeding puncture in the evening are found
    widely flared in the morning. On the other hand, large squares which
    are within a few days of the time of their blooming may receive a
    number of punctures without showing any noticeable flaring. Fre-
    quently a square which has flared widely will be found later to have
    closed again and to have formed a distorted bloom (P1. VI, fig. 30; P1.
    VII, fig. 31), and occasionally such squares develop into normal bolls.
    In squares of medium size a single feeding puncture does not usually
    destroy the square. The destruction of a square by feeding results
    either from drying, decay, or a softened, pulpy- condition of the
    interior which is the consequence of the weevil injury.
    Boils are quite largely fed upon after infestation has reached its
    height. Small and tender bolls are often thoroughly riddled by the
    numerous punctures (Pl. VII, fig. 32). Small bolls so severely injured
    fall within a short time. Larger bolls may receive more punctures
    without being so severely injured. A comparison of the external
    and internal effects in such cases is shown in Pl. VIII, figs. 34, 35.
    Abnormal woody growth takes the place of the normal development
    of the fiber, and a softening and decay of the seeds often accompanies
    this change. One or more locks may be destroyed while the remain-
    der of the boll develops in perfect condition (Pl. VII, fig. 33; PI. X,
    fig. 38).
    After the boils become about half grown the effects of feeding are less
    liable to cause the boll to fall (PI. I, fig. 10). Thle puncture becomes
    closed by a free exudation of the sap and a subsequent woody growth,







    44

    which forms frequently an excrescence the size of half a pea upon the
    inner side of the carpel. An excrescence of this character usually
    results from an egg puncture, and often from feeding punctures.

    DESTRUCTIVE POWER BY FEEDING.
    A glance at the figures in Table VIII (p. 40) is sufficient to show
    the great destructive power of the Mexican cotton boll weevil. It
    may be seen that both in the field and in the laboratory the weevils
    of the first generation are more active in making punctures than are
    the hibernated weevils. These generations overlap too far to attribute
    this difference to the influence of a higher temperature alone, thqh
    this factor will account for a large part of it. A comparison of the
    figures for males alone with those for females alone or with those for
    males and females together shows that it is very conservative to say
    that males make less than half as many punctures as do females. By
    the habit of distributing their punctures among a greater number of
    squares the destructiveness of the females becomes at least five times
    as great as that of the males.
    This great capacity for destruction has been one of the most evident
    points in the history of the spread of the weevil, and deeply impressed
    the entomologists who first studied the insect in Texas. In 1895 Mr.
    E. A. Schwarz, in writing of the work of the weevil at Beeville, said:
    Each individual specimen possesses an enormous destructive power and is able
    to destroy hundreds of squares, most of them by simply sticking its beak into
    them for feeding purposes.

    SUSCEPTIBILITY OF VARIOUS COTTONS.
    An excellent opportunity for observations upon this point was
    obtained upon the laboratory grounds at Victoria by growing within
    a small area plants of several varieties of American Upland, Sea
    Island, Egyptian (Mit Afifi), Peruvian, and Cuban cotton (Algodon
    sylrestre). The Peruvian cotton made a remarkably large growth,
    but put out no squares, so that it does not really enter into this com-
    parison. The Mit Afifi seed was obtained through the courtesy of the
    Bureau of Plant Industry of this Department from a field grown the
    preceding season at San Antonio, Tex., in which circumstances led
    some observers to the opinion that the variety was, to a certain extent,
    immune. The observations at the laboratory were made by carefully
    examining the plants, looking into each square, and removing every
    weevil and infested square found. If there were any distasteful or
    resistant cotton among these, it would surely be found in this way;
    and if any variety were especially attractive to the weevils it would
    be equally apparent. Infested squares being removed, the accident
    of association or proximity would not determine the location of the
    weevils found, but all might be considered as having come to the cot-
    ton with equal opportunities to make their choice of food, and accord-






    45


    ingly their location has tbeell (.o11Sidle'e'd a.1 idic'uiting suc'i i.hoic(t.
    The veriodl of obs.rvatiIon exteils from Ju lie to NoveJiei i', 1.xv.eNpt
    wit4 t(e Cu'iban cot-toln, which wat Is )lLanlt.e( latd -1114 Ia)ltgaLol s1.0 l lt.%I'a4e
    during the latter pIart of August. l'.For the p urpose or l this o I 1maisoi,
    both the varieties and the several plots of the American cotlton will be
    considered tl,)gethetr, as no e'Vide eo ot pretere'ne w Lvas fou ini ailing
    thiem.
    In making ,t (conti)LariSOhl of the results three llleents it, ttst .(, e oll-
    sidered for each variety of cotlonl: First, the nimotier of planlt(s of each
    variety; second, the number of (lays dutrintg which each kitd1 was
    under observation; third, the tota11 n1111belr of weevils found d (om each
    class of cotton. The elements of numbers of l)lauts and t ii les of
    observation may be expressed by the prodluclt of those two factors
    forming a term which we lmay call "p)lanlt-(days." IThe total n1111ber
    of weevils found upon any class of cotton divided by tihe number of
    "plant-days" will give the average number of weevils attracted by
    each plant for each day, and these numbers furnish a means of direct
    comparison and show at a glance the average relative attractiveness
    of each class of cotton. The following table presents these results in
    comparable form:

    TABLE X.-Relative attractiveness of various o cottons.

    Total. Average.
    Number nfested Relative
    Class of cotton, of Plant Veevils' Infested Weevils In t attract-
    n Iat Pliant WeeCvUi Infested. roriatsquare's, ,oi.
    plants, days. found,. squares. perplant squares en
    I per day. per
    weevil.

    American..................... 62 4,920 287 3,507 0.0(158 + 12.2+ 1.(I
    _._________ - I- ,- _
    Cuban------------------------- 5 12:) 11 136 .092- 12.4- 1.6+
    Sea Island-------------------- .................... -8 552 64 1,089 .116- 17.0+ 2.0
    Egyptian --------------------- 8 808 207 2,013 .2564+ 9.7+ 4.4+
    Total of 3 non-Amer-
    ican cottons.......... 21 1,480 282 3,238 .191- 11.5")- 3.3-


    An examination of these figures shows that American Upland cotton
    is less subject to the attacks of the weevil than any of the others, and
    that Egyptian (Mit Afifi) is by far the most susceptible. The differ-
    ence in degree is most plainly shown in the column of "relative
    attractiveness." It would certainly seem difficult to formulate a
    stronger argument for the cultivation of American cot ons alone within
    the weevil-infested district than is presented by these figures. The
    weevils gathered so thickly upon the Egyptian cotton that the plants
    could not produce sufficient squares to keep ahead of the injury, and
    therefore the average number of infested squares for each weevil is
    only three-fourths as great with that variety as with less infested
    kinds, but the average injury to each square was greater than with
    any other.
    The practical application of these observations may be emphasized






    46

    still further by the statement that in spite of the frequent and care-
    ful removal of weevils from these cottons during the entire season
    none of the non-American varieties made a single boll of good cotton,
    so great was the actual weevil injury to them, while American cotton
    with the same treatment developed a large number of bolls.
    The results are still further sustained by observations upon larger
    areas of American and Egyptian cotton under field conditions in three
    localities in Texas, no weevils being removed from either kind. At
    Victoria, Tex., on August 26, 1903, an examination showed that 96
    per cent of Egyptian squares were infested, while an average of 13
    fields of American showed 75.5 per cent. At Calvert, Tex., on Sep-
    tember 4, Egyptian showed 100 per cent infested, while the American
    varieties growing alongside showed 91 per cent. Similar results were
    found at San Antonio. Though growing in close proximity, the Egyp-
    tian produced no staple whatever, while the American gave better
    than an average yield in spite of the depredations of the weevil.
    In accordance with these observations, it appears that in developing
    a variety of cotton which shall be less susceptible to weevil attack by
    far the most promising field for work lies among the American varie-
    ties, and of these the very early maturing kinds are most promising.
    The question of choice of different varieties for food was tested in
    the laboratory by Dr. A. W. Morrill, by placing squares of two kinds of
    cotton, American and Egyptian, in alternate rows in a breeding cage
    (P1. XII, fig. 48), so lettered and numbered that each square could
    be exactly located. Weevils were then placed so that they could
    take their choice of these squares, and observations from 8 a. m. to 6
    p. m. were made upon the location and activity of the weevils.
    Though this experiment was repeated four times, no positive evidence
    was obtained to show that weevils had any choice as to which kind of
    squares they fed upon. Table XI presents a summary of these results.

    TABLE XI.-Breeding-cage observations upon weevil choice of Anwmerican and
    Egyptian squares.

    Num- American squares. Egyptian squares.
    N um _________ _________:
    Ex- Period of ber of Weevils Fpeed- Feed-
    peri- observa- obser- TotalIn- in Egg Total In- ing Egg
    ment. tion. va- used. num- ested, n punc- num- ested. punc-punc-
    tions. be. tues. ber. r. tures.
    tmetures e. tures.

    1 12m. to8
    a.m.... 8 10 16 12 15 5 16 5 12
    2 11.45a.mrn.
    to 9.45
    a.5m.... 5 10 16 5 19 1 16 5 13 8
    3 12m. to5
    p.m.day
    after-...- 5 10 16 7 25 2 16 9 27 2
    4 11.45a. m.
    to9a.m 5 10 16 6 17 6 16 8 14 8
    5 6 p. m. to
    8a.m... 1 18 4 2 7 0 4 2 10 0
    Total 24 58 68 32 83 14 68 29 76 11








    Ill experiimentsI 1 and L tih, Aim'ricail square's weil'ttt atVtackedI in're
    exte'lisively t lani weroe tii Egyptian, witil, in expie'imen',ts ;Is anMd 5
    greater giljuIry Vwas tdon0itte tohe I:gyptian. Ill experimiient, .t11lh1e snallhr1
    number ofrogg 111nd 1,feeding plunctures lmadet in t lltie Egypt ian squares is
    counterlalanced by the larger 1lnum1l1Er (If squares attacked. Although
    the totals from these five tests show slightly loss injury to thle Egyp-
    tian tlihan to the Amuerican squares, it could hardly he expected that
    two arbitrarily chosen series, even if Of" tM MaLlfe variety, would show
    any closer agreement in the points of comparison nmade in tLhis table
    than is therein shown b1)y the American andf Egyptian squares.

    HAS THE WEEVIL ANY OTHER FOOD PLANT THAN COTTON?

    The question of the possibility of boll weevils feeding upon some
    other plant than cotton is one of great importance. It is a well-
    known fact that insects which have few food plants usually confine
    their attacks to closely related plants belonging to the same botanical
    family, or even genus. Accordingly, most of the plants which have
    been tested especially are most closely related to cotton. Four species
    of Hibiscus (H. esculentus, Hi. vesicarius, H. i manihot, H. minoscheutos)
    were grown and an effort made to see whether weevils would feed
    upon either the leaves, buds, or seed pods. In no case, however, did
    they live on any of these for any considerable time, though they fed
    slightly upon some of the parts. Hibernated weevils starved in an
    average time of about 4 days with leaves of either okra or Sunset
    Hibiscus. The buds and seed pods were not formed at that time, so
    could not be tested. Weevils of the first generation, which had had
    no cotton for food, were placed upon Sunset Hibiscus, and these
    starved in an average of 3 or 4 days. First generation weevils, which
    had fed for a few days on squares, were placed upon leaves, buds,
    and seed pods of Hibiscus ,esicarius. Though they fed a little, all
    starved in an average of about 5 days. A lot of first generation
    weevils, fed first for several days with squares, were given leaves,
    buds, and seed pods of okra. More feeding was done by this lot than
    by any other, all parts being slightly attacked. These weevils lived
    for an average of 7 days.
    Numerous other plants, including sunflower (Heliantlius an/imus),
    bindweed (Convolvuluzs repens), the slender pigweed and the spiny
    pigweed (Amaranthus hybrids and A4. spinosus), and western rag-
    weed (Ambrosia psilostachya), and various other species of weeds and
    grasses which occur more or less frequently around cotton fields
    were tested, but in no case was feeding noticed except in the case of
    weevils supplied with pieces of the stem of sorghum, the stems of which
    were cut into short lengths and some of the pieces split lengthwise.
    Upon the exposed, juicy pith weevils fed considerably, but they did
    not puncture through the hard stem to obtain the juice. The sweet




    -. .-.. .. . ....


    48

    sap found in the pith sustained weevils for some time in the labora-
    tory, but where obliged to puncture the stem, as they would be in the
    field, they would never attack sorghum, except possibly freshly cut
    stubble. Among the many plants tried, therefore, none has been
    found to show any capacity for sustaining the lives of weevils in the
    field in the absence of cotton.
    The question of the original food plant of the weevil has received
    considerable attention from this Division, the investigations made in
    Cuba being particularly thorough and conclusive. In that island some
    varieties of cotton grow wild and are perennial. After most dreful
    search Mr. E. A. Schwarz wrote in the spring of 1903: "There is not
    the slightest doubt, in my opinion, that the original and only food
    plants of the weevil are the varieties of Gossypium and here in Cuba
    the variety known as kidney cotton." The investigations o the
    Division of Entomology have given special attention to the possibility
    of the boll weevil breeding on other plants than cotton. Throughout
    the investigations of Prof. C. H. T. Townsend in southern Texas and
    in Mexico and the careful studies made by Mr. Schwarz in Texas and
    in Cuba and the observations made by the writers in Texas every
    plant closely related to cotton has been most carefully watched, and
    the uniform failure to find the weevil upon any other plant makes it
    practically certain that cotton is its only food.

    INSECTS OFTEN MISTAKEN FOR THE BOLL WEEVIL.

    Many species of insects have been mistaken for the Mexican cotton
    boll weevil. Among them the two most commonly reported in Texas
    have been an acorn weevil (Pl. XIV, fig. 55) and a species commonly
    found upon bloodweed or ragweed. The chief reason for the promi-
    nence of these two species is not that they resemble the boll weevil
    more closely than do others, but rather that their habits bring them
    into closer proximity with cotton fields and their abundance has led to
    their more frequent discovery. The acorn weevil has in a number of
    cases been taken in lantern traps set in cotton fields, and the mistake
    in the proper identification of the species has given' currency to the
    report that the boll weevils are attracted to lights, which, however, is
    never the case. There is no authentic record of a single boll weevil
    having been caught at any light. Only very rarely and under exicep-
    tional conditions will the acorn weevil feed at all upon cotton bolls.
    Though the bloodweed weevil (P1. XIV, fig. 54) has been taken
    from cotton plants, no evidence has been submitted showing that it
    was actually feeding thereon, and it is more likely that such specimens
    had merely strayed to the cotton from bloodweed growing near.
    Another species of weevil, Desmoris seapalis (P1. XIV, fig. 58), is
    much less common and therefore less frequently mistaken, but resem-
    bles the boll weevil in general appearance far more closely than does








    , A L '.'. ,. U, L .i'. I


    PI -.T1 VI.


    FIG. 29.-SQUARES MUCH FED UPON. NATURAL SIZE. (ORIGINAL.)


    FIG. 30.-DISTORTED BLOOM, CAUSED BY FEEDING UPON LARGE SQUARE, NATURAL
    SIZE. (ORIGINAL.)





    I


    I













    p









    Pi :' T VII.


    B 4 , lif I


    FEEDING INJURIES ON BLOOMS AND BOLLS.

    Fi'l. :1. Blooms distorted by fiti.li,.. piitl'urv'-. -,*t'ni but iillUrft',ti. two-thirds natural size: iu'.
    .;2. small 1,0ll rii'lll.1, l-iy -'iii imunctures. natural size: tiz. :8: 1on e lock ,'i boll ,Ic-Itrv.,-1 by
    1int', iiw,. puctures, two-thirds natural size. (Oriiiinil.


    . u U .. ;*




    F












    I.







    49

    either oif tlie species previously inentioiedl. 'l'llis ilsect, haIs beenll
    found attacking white prickly poppqy ('ArY,'m oln i/,,t) aLid L tllnoil)le-
    weed (](A 1Ii i ll .sit (/r'tl'iZ(tis) iill the sl)rilg, aund J olal)r l y lbl edI.l s lon
    Prioeop.is d.inift Nui.t.t atIal tiKe4 broad-lhavtd (gu1 tiii la 1l ((,ril/bi ,
    s8110(1r1k(l).
    In guiceral tile foot habits of ainy species are aiioiig its (l istilncti ve,
    specific' characters, anlld as the struci.t ral diffcrenices are easily over-
    looked and difficult of appreciation by atiyoliei ullaC(laillteId with the
    careful study of insects, a rather full, thoughll by 1no ;ealls complete,
    list is here given of the species which have beelii reporteil to tlhe
    Division of Entollmology as having been confused with tlie bo1) weevl."
    Many of the most common species will be found figure(l aillmog tihe
    illustrations. The scientific names of the insects are given because
    they are definite and refer positively to a single species, whereas tie
    common names are used so loosely that the same name may be applied
    to a number of species having possibly similar habits. The boll weevil
    is included in this list, and figures of the adult are given in thle plates
    to facilitate comparison. In many cases no common name has yet
    been given to the species. Seven of the species mentioned attack
    living cotton and five species are found feeding only in decaying bolls.
    The occurrence of the remainder upon cotton is merely incidental.

    Insects often mistaken for the boll weevil.


    Scientific name. Common name.

    WEEVILS.
    Anthonom us yraudis Bobh ---. Mexican cotton boll weevil
    Anthoinonm s albopilositsDtietz------------------------- ..............................
    Authonomus prunicida-- ..- I Plum gouger----------
    Balaninus uniforni is auct - -. Acorn weevil------------
    Cen trinus pen icellnus Hbst.................................
    Centrinus picumnus Hbst ------------------------------
    Chalcodernmus eneus Bobh ..... Cowpea-pod weevil .......
    Desmnoris scapalis Lec .... .. .. ...........
    Desmnoris constricts Say -- .- ... ..........................


    Dorytomus mucidus Lec...----
    Lixus lasicollis Lee --------1I
    Coccotonris scit tellaris........
    Baris striata Say --...---.......
    Baris transversa Say.--------.
    Anthribus cornu tus Say.......
    Arcecerusfasciculatus DeG ...


    Blood-weed weevil
    Apple curculio ---------....
    Striped Baris.-----------..
    Transverse Baris --.......
    Horned stem borer .....
    Coffee-bean weevil


    Epiccerus imbricatus Say-...... Imbricated snout beetle ..
    Hylobius pales Hbst-..--- -- .............................
    Rhynchites iexicanus Gyll ... Mexican rose beetle--.....
    Tych ins sordidus Lee ..----...--..... ..............................
    Ophryastes bituiberosus Shp .................................
    Trichobaris m ncorc Lee --.--- Tobacco-stalk weevil...


    Plate
    Usual food plant. figure.



    Cotton squares and bolls. XIV,.52,53.
    Plums-------------- ------------X~,7
    Plum s ..................... X IV 57.
    Acorns ....................- XI-V 55.
    Beetle in flowers ......... XV, 61.
    S.do .. .... ........... ..----------...........
    ('owpea pods ............. .XV, (, 64.
    Broad-leaved gum plant XIV, 58.


    Willow..... ...........
    Ragweed (m bn/,rosia spl)P .) -
    A pple -- ---- -------
    Stems of ragweed........
    Roots of cocklebur ......
    Cotton stems .............
    Coffee beans and old cot-
    ton bolls.
    Omnivorous --.....--..--.-...

    Beetles attack rose-......
    Common in cotton fields..
    Found on cotton..........
    Tobacco stalks ...........


    XIV,.54.
    XIV, 56.

    XV, 59,60.

    XV, 62.

    XVI, 69.


    aIn the preparation of this list we are under obligations for assistance to Mr.
    F. H. Chittenden, who has also furnished information in regard to the food habits
    of the species.
    21739-No. 45-04--i-4






    50

    Insects often mistaken for the boll weevil-Continued.

    plate
    S'i.utific name. Common name. Usual food plant. figurPlate
    figure.

    OTHER BEETLES.
    Monorcpi-cpudis vespertim us Fab. ............................. Larva in grass roots ..... XVI, 70.
    Notoxirs iniodon Fab--........---------------------- ............................. Larva in ground-----
    .A t.ta c-rfy/plt Say..----------- Cotton-stalk borer ---..---. Cotton stalks ---------- XVI, 68.
    librns (iitdalis MeLs--------............------...-----------------............... Decaying bolls .................
    C'a irpnph s It, hemi ipteruis Linn ..------------------------- ............................. Deelops in decaying bolls' --------..-.
    C rpophilus diimidiatus Fab -------------------- ... do -------..- ......... ...........
    Epur'a wa'stiua Linn ---------- ---- ------------------ ---do .................... ....
    (',th r'tus yleil/e at .usDuv...... Grain beetle----=--------- ----do.....--.............
    Tri-iholiin m ftrrugineu nm Fab.... Flour beetle----------- .............. Attacks seed.----------... I....-..
    BU(:GS AND OTHER !NSECTS.
    Honilodi.srt triquetra Fab - -- Sharpshooter-----------............ Cotton stalks --.... .........----- XVI,65,66.
    (floimctojpit unidata Fab ------ Waved sharpshooter--------. .do -----...-----------........... ...........
    Dysdercus suturellus H-Sch ----.... Cotton stainer---....---. Cotton bolls-------------- XVI, 67.

    IS COTTON-SEED MEAL ATTRACTIVE P

    LABORATORY OBSERVATIONS.

    On account of the popular impression that cotton-seed meal will
    attract weevils it has been necessary to conduct a rather full series of
    experiments. To ascertain the possibility of using this substance as
    an attractant for the weevil in field work three series of laboratory
    tests were first made. The weevils used were obtained from the same
    source in all tests. The first series was designed to test the ability of
    the weevils to live upon cotton-seed meal alone as a food. The sec-
    ond series was intended to show whether the weevils would prefer the
    meal to cotton leaves as an indication of the possibility of attracting
    hibernated weevils before the formation of squares in the spring.
    The third series was planned to show whether the weevils would pre-
    fer the meal as a food when squares could be easily found. The
    cotton-seed meal used was obtained fresh from the oil mill and the
    experiments started during the latter part of November.
    Weevils fed rather sparingly upon the meal in Series I. It did not
    seem to agree with them as a food and they showed no special inclina-
    tion to feed upon it. Twenty-three of the 24 weevils confined upon
    meal alone died in from 2 to 13 days, showing an average length of
    life of slightly over 6 days. These weevils either starved to death
    rather than eat the cotton-seed meal or else they were not able to eat
    it. The dry and empty bodies of all dead weevils showed that death
    was caused by starvation and not by disease. Being entirely covered
    with the fine meal did not seem to have any bad effect upon them.
    As weevils without food or water showed an average length of life
    slightly over <; days, agreeing exactly with the period in this test, it
    appears that cotton-seed meal is not only not a food for the weevil,
    but also that it is not capable of prolonging their lives to any appre-
    ciable extent.


    -J








    In Series II 21 weevils were conflile'dr witl1 fresh 't 01.AIn leave's and
    cotton-seed inmial as food. I)iuing 1 th 29.7 "w wvil-dlays" thinat ihis
    experimnillt was conltillnued hut Jnit, weevil ldieid. TlIM, av'rag iug,'riod
    of the test for each weevil was 14 days. '1The w.eevils feid almost
    wholly uipo) leaves. Occasionally ()onIe would f((eedl a lit.tl- n tihe
    meal, but they certainly preferred t0he leaves, alnd tli resell s show
    that leaves alone were responsilhJe for the longer life of these wee.'iLs.
    The 20 survivors were placed in hibernation D)eceInler f-1, I"01, but
    all died before April 15, 190)3.
    In Series III freshly picked squares were placed with the lemeal to
    see which would attract the weevils. Fresh meal, as well as squares,
    was supplied at frequent intervals. During the 15S weevil-(lays"
    that this test continued not one of the 10 weevils died. The average
    period of the test was almost 16 days, and after it the weevils were
    placed in hibernation, but all died before April 15, 1903. In only one
    instance was a weevil observed feeding upon the meal. From this
    test it was evident that cotton-seed meal has not the power to attract
    weevils from squares, even when the latter have been picked for
    several days.
    In spite of the complete failure indicated by these results, a series
    of field tests was made during the late fall of 1902.

    FIELD TESTS.

    In order to settle this question finally, two series of field tests were
    made, one during the fall, when weevils were abundant but full-fed
    and cotton still standing, and the other during the early spring, with
    the view of attracting weevils as they came from hibernation before
    cotton began to square.
    Fall of 1902.-Cotton-seed meal fresh from the mill was placed in
    10 cheese-cloth bags, which were shaken so that the fine dust from the
    meal covered the outside of each bag. The bags were numbered and
    then tied to cotton plants in infested fields at about the middle of the
    plants. The bags were so distributed as to test fields in which the
    following conditions prevailed: One field entirely black from frost,
    one nearly black, one about half green, and one still entirely green.
    The number of weevils on the plant to which the bag was attached
    was noted each day to ascertain in a general way the number of wee-
    vils which would be very near the meal and able to reach it in the
    ordinary course of travel over the plant without having to fly to it.
    Weevils on adjacent plants would naturally come within the sphere
    of influence if such existed, but they were disregarded. After the
    failure of the meal to attract weevils in the field became apparent,
    weevils were caught and.placed upon the bags to see if they would
    stay there.
    Altogether 65 observations were made, covering a period from Novem-
    ber 24 to December 16. The weather was generally cool, averaging






    52


    about 61 F., mean temperature, and cotton had ceased to grow.
    Counting each weevil found at each observation, only 5 were found
    upon the 10 bags of meal. Of these 5, 3 were hidden in the folds of
    the cloth for shelter and were not feeding. One weevil was counted
    twice and was the only one found that appeared to be feeding upon the
    meal. During this period a total of 163 weevils was found upon the
    top parts of the plants to which the bags were attached. This is con-
    siderably below the real number present, because in many instances
    this examination was not made, and doubtless weevils were overlooked
    even when examination was made.
    At various times 27 weevils were placed directly upon the bags of
    meal and given every opportunity to show whether they would stay
    thereon if they accidentally found the meal. Only one of this num-
    be& stayed upon the bag for 24 hours, and this one remained in the
    shelter of the cloth.
    The unattractiveness of cotton-seed meal for the weevils seems
    absolutely proven so far as fall conditions are concerned.
    Spring of 1903.-These tests were intended to show whether hiber-
    nated weevils would be attracted to the meal before squares were to
    be found in the field. Two series of experiments were planned, using
    four bags of meal in each. For the location of the first series a field
    was chosen which was known to-have been badly infested with wee-
    vils up to December 18,1902. This field was not replanted with cot-
    ton in 1903, nor was there another field in the vicinity, so that weevils
    coming from hibernation would find no possible food except the meal.
    A number of live hibernated weevils was taken from this field, so that
    there can be no doubt of the presence of many of them. The bags of
    meal were placed near apparently favorable hibernating places.
    Fifty-five observations were made under these conditions, but not
    a weevil came to the bags of meal.
    For the second series a field was selected in which occasional seppa
    cotton plants were found. The plants had been allowed to stand
    through the winter in this field, and hibernated weevils were quite
    abundant. The bags of meal were here attached to stakes driven
    beside seppa plants. More than 50 observations were made after
    weevils were known to be out of their winter quarters. Nine weevils
    were found upon the seppa cotton plants beside which the bags of
    meal were placed, but not a weevil was found on the meal.J
    SOnly one conclusion can be drawn from these experiments. Under
    no conditions will cotton-seed meal serve as a food for the weevils,
    and it shows no power whatever of attracting them.
    THE POSSIBILITY OF BAITING WEEVILS WITH SWEETS.
    ATTRACTIVENESS OF VARIOUS SWEETS.
    On account of the considerable publicity given the theory that it
    might be possible to destroy the weevil by attracting it to sweetened
    poisons, a number of experiments were performed along this line.
    t
    a
    A






    5,

    Iii the course of this work IMr. ( II. 1 luarris eI.Jtllo-1l0 in0 tlial lallra-
    tory tests a large varii'Vy ()f sweets. \\'hit.e g'raiiLnlattNd sugar, Iw% oI)ri
    three grails, i-f l)'Ov ii.stigar, t W() fr tbhriL grades otf l' moJlafsses., adl( Ilihe
    best strained oti l(nfly were along tIhe sweets tried I''he ondtiIition1
    were sll(h as to lead tlie weevils I( eat, tlie sweets if tliey woil 3%1111,vjr
    do so. Ti'le only alternative otfTered then for fo)o1 was a satippl13' of
    rather o(l cottmo leaves such as W(,1'(ilIs nieveri t, m(cl in lt.1( fild1l. In
    spite of the unftavorablh c iditi(Is for getting at the real clhI(oi('e of
    the weevils they showed little inclination t[ feed upon tIlie sweets
    except in the case of honey, which seemed to attract thlevim (quite
    strongly. Many weevils fed upon the unattractive leaf tissue owr upon
    the broken end of the petiole rather than upon thlie sweets.
    The result of Mr. Harris's experiments with undiluted molasses
    applied to plants in the field as summed up in lhis own words was that
    "nothing indicated that the weevils were attracted by the odor of
    sweets." Honey was then tried, and this did attract a few weevils.
    Mr. Harris's general conclusion, based upon the results of his experi-
    ments, was that "while a high grade of sweets seemed to have more
    attraction than a cheaper grade, neither can be depended upon to
    attract the weevils for poisoning."
    ATTRACTIVENESS OF SWEETS TO HIBERNATED WEEVILS IN LABORAT(O)RY.
    The sweets used in these tests were of three kinds: High-grade
    molasses, common molasses, and light-brown sugar. The weevils
    were brought in from the field and left for one week without food or
    drink previous to the beginning of the tests on April 2, 1903. Three
    weevils were used with each kind of sweet, the latter being in their
    strongest form and the sugar in a saturated solution. The inclosing
    apparatus was formed by placing two bottles mouth to mouth with
    sufficient space for air, but not enough for the escape of the weevils
    between them. In the bottom of one bottle was placed the sweet and
    the second leaves of cotton in the bottom of the other. The weevils
    were then inclosed, and the cages thus formed were placed in a hori-
    zontal position in the dark to eliminate every possible influence of
    direction of light, relative elevation of food, etc. Thle food supplies
    were renewed occasionally, and the location of tlhe weevils relative to
    the food in each cage was noted frequently. The weevils were counted
    at each observation. The results of these observations are briefly
    summarized in the following table:
    TABLE XII.-Attraction of various sweets vs. cotton, second leaves.
    Number Number. Number
    Character of sweet. of ob- of wee- of wee-
    serva- vils on vils at
    tions. cotton, sweets.
    Best molasses, cage 1...............................................-------------------------------------------0 25
    Best molasses, cage 2- ----------------------------..................... ................... 13 29 5
    Common molasses, cage 3-----------------------...........................------.............. 18 42 4
    Brown-sugar sirup, cage 4 ....--------..-..-----.......--------------------------.................' 21 48 8
    Total--------..-----..--....------------------------------------..... ..............................' 72 144 18






    54


    These figures become even more striking in consideration of the
    fact that the cotton leaves were often purposely left until they became
    moldy and decayed or dried and wholly unfit for food. It was at
    such times that most of the weevils sought the sweet in preference.
    Should we leave out of the account the weevils found at the molasses
    or sirup when the cotton was unfit for food, the number attracted
    there would be reduced fully one-half. In either case the fact remains
    that none of the sweets can be said to have attracted weevils from
    the cotton leaves.

    INFLUENCE OF SWEETENED WATER UPON FEEDING OF WEEVILS ON
    COTTON PLANTS.

    It is easy to demonstrate that weevils will in confinement feed
    upon sweet solutions. To prove that they will show the same attrae-
    tion to it in the field is a far more difficult matter.
    For the purpose of these experiments, cheap molasses was used,
    mixing 1 part of molasses with 25 parts of water, as is generally
    recommended in spraying formula. Three pairs of young plants
    which had not begun to square were then selected from those growing
    upon the laboratory grounds. The plants in each pair were of equal
    size, and both in healthy condition and standing closely enough
    together to be both covered by one cage. One plant of each pair was
    then dipped in the sweetened water, while the other was left in its
    natural condition. In each of the cages 10 weevils were then placed
    upon the ground and midway between the bases of the plants. The
    object of the test was to see which plant, the treated or untreated,
    would attract the larger number of weevils. During the first three
    days observations were made several times each day. Weevils found
    upon either plant were counted at each observation.
    A summary of the observations made on the first day before the
    liquid had dried showed 15 weevils upon the sweetened plants and 16
    on those not sweetened. These results were so remarkably even that
    no attraction or repulsion could be ascribed to the liquid before it
    dried.
    During the ten days covered by the observations, however, 63 wee-
    vils were found upon the unsweetened plants and only 45 upon those
    sweetened. The weevils fed largely upon the petioles and somewhat
    upon the blades of the leaves and the main stems of the plants. No
    indication was observed of special feeding upon the "gloss" left by
    the drying of the sweetened water. In each cage the normal untreated
    plant was destroyed before the treated one. During the first half of
    the observations 52 weevils were found feeding upon the unsweetened'
    plants and only 32 upon the sweetened. Only after every leaf on the
    untreated plants hung black and dead, while the sweetened plants
    were in much better condition, did more weevils attack the sweetened
    plants.

    'i
    .:i






    55


    Not. inly d(id these tests slhoWI Ilat imtola.sseMA s i,-,iI oIt( iI I, lIas 111, altt H Ir-
    tioe foir tih, weevils, i1t, also that. lit e Mtic'k"y coating I I afteL'lr tlIl '
    liquid Ias d(ried1 ac'ts uore1I as a Iositivi'V re'Iellnlt to)1 l1'tiei.

    FIELD TESTS FO-i I IBERNATED WEEViLS, I'SIN; I'1RE .MI()IASSIl'S.
    As a final experini,'n, to settle tl(e possible, uset'ulinitess ,,f ,( ,,'la,.,sses
    in tihe weevil tligit, a large series of tests was iidlWA l'rtLake'i, iii iO livld
    to see if the purely, undilted m111olasses, woull d 1ot. prIv' alt lrait iv o
    weevils a s they cam2e from hilbernation. ITo isniure La outiu('oius sup-
    ply of fresh molasses a test tlube was nearly fili(led an(Il thel n rthelir
    tightly plugged with a small stopper wound with ottoil. !The' l1tie
    was then fastened in an inverted pI)osition Ilo the top ) Of a sIlk(' ;Iaout
    2 feet long, and as the molasses gradually oozed( through tl o1114 ttoIn
    it ran slowly down the stake, forming a streak of con itiuotuisly freshly
    molasses a foot or more in length. Trlie supply would thus last 'for
    several days and was then easily replenished. This apparat.us, s
    shown in Pl. XII, fig. 45, was then placed beside a vigorous seppa olt-
    ton plant in the field at the season when the weevils were lbeginninig
    to leave their winter quarters and seek food to break their 14g fast..
    Both high and low grades of molasses were employed in these tests,
    three tubes of each being used. Altogether 84 o)servat ions were iale
    between April 24 and May 15, 1903, during which period most of lthe
    weevils emerged from hibernation.
    The results again proved disappointing, for only a single weevil
    was ever found at the molasses. This individual sipped occasionally
    at the sweet, wandering up and down the tube in the intervals. It
    did not appear to be satisfied and did not remain long at or near tile
    molasses, but flew away and was not found there again.
    The failure of the molasses to attract was not due to tlhe scarcity of
    weevils in the field. During the period of observation 2\ we(ev\ils
    were found working upon seppa cotton very near the molasses tubes,
    and certainly within reach of its attractive influence, provided it had
    any. More weevils were also found in the same field, but at some-
    what greater distances from the tubes.
    During the warm days toward the close of the experiment many
    butterflies, mostly TJanessa a/aldun: and some Anosia plvitpp u.', canet
    to the tubes. A few specimens representing several species of beetles
    and many ants were also found.
    None of the experiments made, either inl the laboratory or in tlhe
    field at Victoria, Tex., has shown that weevils are attracted in even
    the slightest degree to any grade of molasses, either in its undiluted
    or diluted form. No sugar solution has been found to possess any
    more attraction than does molasses. Honey appears to be an espe-
    cially attractive sweet, but is too expensive for use in this manner.
    Considering the facts that these experiments have been much more
    numerous and that they have covered a much broader range of con-






    56

    editions than any previously performed, we must conclude that it yet
    remains to be shown that sweets of any kind have any value in the
    problem of controlling the boll weevil.

    FEIGNING DEATH.
    This interesting habit of the weevil is its first resort as a means of
    escape from its larger enemies. It has been the basis of many ma-
    chines designed to jar them from the plants and to collect them in
    convenient receptacles. If jarred from the plant, the weevil falls to
    the ground, with its legs drawn up closely against the body and the
    antennae retracted against the snout, which is brought inward toward
    the legs. The position is characteristic and can be more easily shown
    than described. See P1. I, fig. 2. In this position it often remains
    motionless for some time. If further disturbed, so that it finds that
    its ruse has failed to conceal it, it will start up quickly, run a little
    way, and again fall over, feigning death. The color of the weevil
    so closely resembles that of the ground that it is quite difficult to find
    a fallen individual so long as it remains quiet. The habit is of great
    value in protection. If left undisturbed until it believes danger to
    be past, it recovers its footing and returns to the plant.

    REPRODUCTION.

    Under this general heading we present some of the most interesting
    observations which have been made upon the habits of the boll wee-
    vil. The relation of the sexes, the evident selection of clean squares
    for egg deposition, the great destructive power of the weevil, the
    rapidity of development, and the influence of varying temperatures
    upon its activity and development may also be classed as among the
    most important as well as most interesting observations.

    METHOD OF MAKING FIELD OBSERVATIONS UPON WORK OF
    WEEVIL.
    For the purpose of field study large cages (3 by 3 by 4 feet) were
    made, the covering being of fine wire screening (P1. IX, fig. 36).
    Uninfested plants having plenty of squares were found by a careful
    examination of each square and inclosed by the cages. The number
    of weevils placed in each cage was varied according to the number of
    squares within, ranging from 2 to 5 at various times. In making the
    daily observations the cage was entered and each square examined.
    Each square found attacked in any way was marked with a numbered
    tag containing full data as to the lot of weevils and the number pres-
    ent, date, and nature of injury (Pl. IX, fig. 37). After all weevils
    had been found the cages were removed to new uninfested plants for
    another day's work. Close watch was kept upon all tagged squares
    upon succeeding days, and every important change taking place in
    each square was added to the record on the tag. The special points








    B... 4 .... U. ', I ,,V .of A ,


    EXTERNAL AND INTERNAL INJURY FROM FEEDING ON BOLLS.
    Fig. :'i. -':xterinal appearance ,f large )oll much fed upon, iallnral Mi/g: 11g. 35, internal i appinir-
    ance ,tf :arui boll. natural size. (Origiiaul.)


    PL A TI VIII.




    .....................







    ' I I f .'' .


    FIG. 36.-CAGES USED TO CONFINE WEEVILS IN FIELD. (ORIGINAL).


    FIG. 37.-PLANT SHOWING TAGGED SQUARES FROM CAGE WORK. (ORIGINAL.)


    F'A T. IX.


    H -1




    -- --







    PLA X.


    EGG AND FEEDING PUNCTURES: EFFECTS ON SQUARES AND BOLLS.
    Fig. :-w. Boll -hiwi-g two locks (ILmsTrI iy*d by two f'r.liw.i J punctures made by a male \\,.c\ i. two-
    thirnils natural -izi.-: fig. 39, square -i,,wiiig external appearance of two egg 'li,'t n-i..s. natural
    si.C: tihr. 4,. wart formed on side 'i'f -4iitr in lilAiiii an .,g unr.Irtur natural size; fi,. 41, ,gg
    deiiosited on inside of ,ilrpel of a boll, twOu-thiri, naturalri/x fig. -l2. normal ind fired
    squares, natural size. (Origimal1.)


    B t, 4 5 '. L ,'- . .. '" UL S! l ...


















    I
    .1

    a












    ij






    57


    noted in ea'ch caIse, so far as was lpossil)E,, were: 'Ti'<1, I',iriii10 il ( it
    distinct wart.; ti e 1Of 1 larinig, yel(winHg, a111 falling; tll, emergenle.
    of adult; lpr'esence )f a parasite'; deal0 iof larva, piipaL, ti. A very
    complete history of each square was thus obtained. During thlie sea-
    son of 1903t lthee special periods were selected fmtI tr sltidy of tthis kind.
    The first was taken (during the early part of(l .Itn wliei II hil)(TIrlatel
    weevils only were active, the secCfd was takeii in August for the
    work in midsummer, and the third in tl1e latter part of ()ttoler for
    the study of the development of late weevils. Altogether iln these
    three series over a thousand squares were tagged and recorded.i The
    work of males was compared with that of females in tl his way, as
    were also the developmental periods in squares and bolls. Although
    requiring a great deal of time and close attention, the numerous defi-
    nite observations obtained abundantly justified the work reqIluired.

    FERTILIZATION.

    AGE OF BEGINNIN(; COPULATION.

    After the adult weevils have left the squares a certain period of
    feeding is necessary before they arrive at full sexual maturity. This
    period varies in length according to the effective temperature p)revail-
    ing and Appears to bear about tlhe same ratio to tlhe developmental
    period as does the pupal stage.
    Among the many weevils kept from emergence till death for the
    purpose of ascertaining the length of life without food, copulation
    was never observed. With weevils fed upon leaves alone the period
    preceding copulation is about twice the normal length in the cases
    observed of those having squares to feed upon.
    During the hot weather this period appears to be on the average
    only about three or four days in length, while as the weather becomes
    colder it increases gradually until weevils may become adult, feed
    for a time, and go into hibernation without having mated.' A single
    union seems to insure the fertility of as many eggs as the average
    female will lay, and its potency certainly lasts for a period fully equal
    to the average length of life.

    SEXUAL ATTRACTION AND) DURATION OF COPULATION.
    Trhe distance through which the attraction of the female will influ-
    ence the male varies extremely. To ascertain how far the attraction
    might be exerted in the case of the boll weevil, 2 females were con-
    fined with food in a small bottle covered with cheese cloth, and the
    bottle was then placed in a horizontal position inside a field cage and
    near its top. Within this cage were 3 males which had been confined
    there alone for 4 weeks. The bottle containing the females was so
    placed as to be within a few inches of the top of a cotton plant upon






    58

    which the males were working and touching the leaves of the plant,
    in order to afford the males access to the bottle without having to fly
    to it.
    Close watch was kept, but during 11 days not a male was seen to
    go near the bottle. At the end of that time the females were taken
    into the laboratory, as was also one of the males from the cage. All
    were removed from squares and, being placed upon the table, were
    brought gradually nearer together. The male paid no attention
    whatever to the nearest female until brought within an inch of her.
    He then went directly to her. The sense of smell appeared to guide
    his movements. The fact that this male mated readily with both of
    the females used in the cage shows that the only reason for failure to
    attract in the cage lay in too great distance separating the sexes.
    These observations are entirely borne out by those made in the
    field. The fact appears to be that the sexes are attracted only when
    they meet either on the stems or upon the squares of a plant. The
    comparative inactivity of the male has a bearing on this matter.
    The general conclusion is that instead of seeking widely for the
    females, the males are content to wait for them to come their way.
    The greater comparative activity of females is shown in the study of
    their food habits.
    In a number of cases that were timed the average duration of the
    sexual act was very nearly thirty minutes.
    DURATION OF FERTILITY IN ISOLATED FEMALES.
    A number of females which were known to have mated were isolated
    to determine this point. Although neither limit was exactly deter-
    mined, the results proved very striking. Several of these females
    laid over 2215 eggs each and nearly all of them proved fertile. Select-
    ing three cases in which the facts are positively known, it appears that
    fertility lasted for an average of something over 66 days and that
    during this period these females deposited an average of nearly 200
    eggs. The maximum limits may possibly be considerably higher than
    these.
    OVIPOSITION.
    AGE OF BEGINNING OVIPOSITION.
    Normal oviposition seems never to take place until after fertiliza-
    tion has been accomplished, but it usually begins soon after that.
    Observations upon the age at which the first eggs are deposited can
    be made more easily and more positively than those upon the age at
    which fertilization takes place. In a general way, therefore, the
    observations here given may be considered as also throwing light
    upon the time of beginning copulation.
    In the breeding of weevils from eggs deposited by hibernated females
    a number of observations accumulated upon this point and another
    series was made in the fall of 1902. The results of both series are
    given in Table XIII. :|
    ' :







    59


    TAL XIII.-Atf/ f /'i.if u ul ,lmi pmon i iin.

    WEEVILS OF FIST (iENERATION. I lM.


    I)ato adult.


    I)Lti' Ir fiI-t I'gg.


    INilib I .-li" l ,-1,, W .,-vil
    nm l..it i- rL M
    nhiili~l4. lilni,. 'Iiiy'n.


    1iM f111M .
    June 8 to ...... ... ..... ....... .............. Juno 17 t I .......
    J u ne 1 ..... 1... . .. .. J uno 19........... ...
    J une 11 .... ................. ....... June W ........
    Juno 12 ... . .. . . -. . do .... I
    Do . ... .. .. ... ..... Junie Il .
    June 13 ............................ ...... June I .
    June 13 to 14 ................................... ..... do ... .... .
    J une 14 .............. ........ ................. .....do ..... ..
    T o ta l .................................. ..... ... .... ... .....
    A average tim e after adult ...... ............ ........................


    *1
    .3
    4
    .37


    WEEVILS BRED IN FALL OF 19r2.

    1902. 1M2). .
    September 4to 5---------------------------- September17------3
    September 9 ................................... September 16 ........ 5
    October 2 ...................................... October 16i ........... 4
    November!l to 10 .............................. November 1I to 17... 7
    November 11-................................... November 19 :1
    Total ------------------------------------------------------- 22
    Average time after adult....-...................... .... ..... ....... ........ ..


    2. I :.7 tI
    II. (I I1. (I
    I i X1.i1
    4.11 4 II
    7.'' 14.0
    5.1. il i. II
    4.0 If.I)
    5 i i 1 5 1 1 .1.
    . .I l5tl. II
    . ... . -". 5 #-


    12.5 37.5
    14.11 I 56. I
    7.1 I 49.11
    S.11 24. o

    .......... ail. 5
    .... .. .... i l) +


    The average time of 5.5 days, as shown by the first generation, is
    probably about a day and a half longer than the minimum average
    period during the hottest weather, while the 0-day average found from
    September 4 to November 11 is considerably short of the maximum
    average just before hibernation.

    EXAMINATION OF SQUARES BEFORE OVIPOSITION.

    In the course of a great many observations upon oviposition it
    was found that females almost invariably examine a square quite
    carefully before they will begin a puncture for egg ,(deposition. This
    examination is conducted entirely by means of senses located in the
    antennae and not at all by sight. In fact, the sense of sight appears
    to be of comparatively small use to the weevil.
    In regard to the actual time spent in the work of examination before
    beginning a puncture 60 observations were recorded. These show
    that the average time is over two minutes.
    This examination of squares is made by females only when they
    intend to oviposit. Males have never been observed acting in this
    way, nor do females generally do so when their only object is to feed.

    SELECTION OF UNINFESTED SQUARES FOR OVIPOSITION.

    So unerring is the sense by which examination is made that in a
    few cases it was able to discover an infested condition no external sign
    of which was visible to the writer's eye. A female which was under
    close observation examined the square given her in the usual manner,
    but though evidently searching for a place to oviposit and anxious to






    60


    do so, she plainly objected to placing an egg in that particular square.
    The writer again examined the square carefully, but found no sign of
    infestation and replaced it in the observation cage. Again the female
    made her usual careful examination and still she plainly refused to
    oviposit. Upon removing the covering from the square it was found
    to contain an egg, but the puncture made in depositing it had healed
    so smoothly that it had thrice escaped observation. The same female
    was then given two squares, one of which was known to be infested,
    the latter being placed nearer her. She examined it carefully, then
    left it, and went at once to the clean square, in which, after the usual
    examination, she deposited an egg.
    The acuteness and accuracy of the preliminary examination is also
    well shown by the fact that when provided with more squares than
    they have eggs to deposit they rarely place more than one egg in a
    square. It was frequently found, however, that when a female depos-
    ited just as many eggs as there were squares present she would place
    two eggs in one and then make only feeding punctures in the remain-
    ing square.
    The observations were made upon a large number of females; so
    there can be no doubt that the habit of selection is general. The
    conditions provided in these experiments were intended to resemble
    those existing in a slightly infested field early in the season, where each
    female could easily find an abundance of clean squares in which to
    deposit her eggs. Therefore only those cases were recorded in which
    the number of squares present equaled or exceeded the number of
    eggs deposited. Where a totally infested condition is reached no
    choice between infested and uninfested squares could be exercised,
    and then unless the female happened to be in a condition to refrain
    from oviposition she would be forced to deposit more than one egg
    in a square.
    Not only do females show a strong inclination to place only one egg
    in each square, but they also object to making both egg and feeding
    punctures in the same square. That these conclusions are well
    grounded may- best be shown by giving a summary of two long series
    of observations, the first made in the laboratory in the fall of 1902
    and the other made in the field partly in the fall of 1902 and partly in
    the spring of 1903.
    LABORATORY OBSERVATIONS.

    Nine females were used in this series of experiments. The time
    followed varied with each individual, but ranged from October 23 to
    December 18, 1902. During this period a total of 868 uninfested
    squares was supplied to these 9 females. Of these squares 238 were
    not touched, while 630 were punctured, either for oviposition or for
    feeding or for both. The general results are here summarized in
    tabular form.







    61

    TABLE XIV.-SV/-Chf ichan ief q/inu ra'n c ,lt r /lbalin eaf fi'rilfin, In h,,,'ijf)x/;IhI',.


    No. I.I I AIl "4ir1.t l S Ul 4 r i t1 SwiIhIM,1-1'4
    toffe- Pt dle d.'ri (l.>f s,.rvutin. I1 Un l." ,. wit WLi1' ,-nl.. lt 1 ,"
    malt'. M'^*"llited. "lv. titll Imtl -"' .l
    male. OK~~~~~egge h. II' 16IC1CICd fllVII'l

    1KC.
    1 (October 23 to November 15 .... -1 72 .') 1 :5
    2 Othtolwr 21 tem Nmvtnmlnr 27 .... 171 rM '2 3 71
    3 Oktober 251 to November 7 ... 9ti 74 4 % I
    4 I( tober23ttoberrt-(to era1.. ..... :t. 13 II 4 9
    5 Octolxr 2V to (k-tober 28<....... 3s :91 1 2 :.' 3
    6 November 10 to Devember 5 ... 1 .1 3 :14 11 5 1 51
    7 November 10 to November 25. 75 41 3 7 1
    8 i November 11) to December 18 .. 17 4 1 12 1 45
    9 November 1 to Decembt-r12-.. 1:x1 63 I 16 :
    Total ...................... Ri 477 119 l1I1 21 0


    A little calculation from these results shows that S2..)+ pwr cent of
    all squares attacked received eggs and that 91.7+ per cent of all
    squares ovip)osited in received only one egg each. The squares which
    were fed upon only formed 17.5- per cent of the total number
    attacked, and those receiving both egg, and feeding punctures consti-
    tute only 3.8 per cent. The squares receiving two eggs each also form
    3.8 per cent of all the squares which received eggs only.
    The tendency to confine egg and feeding punctures to separate
    squares is strongly emphasized by the fact that in 17 instances, in
    which a total of 116 squares was provided, 91 received eggs only, while
    the remaining 25 were fed upon only; another total of 78 squares
    received 88 eggs in 72 of them, while the remaining 6 were fed uIpon
    only. As these two lots include nearly one-third of all the squares
    punctured, the tendency may be clearly seen.

    FIELD OBSERVATIONS.

    For one series of observations 500 infested squares were picked
    promiscuously in the field between May 28 and June 9, 1903.
    A previous field examination was made about the middle of Septeinm-
    ber, 1902, and this furnishes some very interesting comparisons as to
    the weevil's work upon the squares, especially at the beginning of the
    infestation and after it had reached its height. To facilitate an easy
    comparison, the results are arranged in Table XV.




    I


    62

    TABLE XV.-General results of observations upon selection of squares.

    SSquareswith Sqtares with
    Squares with n both egg Squares fed
    Squaresre tand el
    S1 egg each. egg eah andpu feeding on only.

    Sue ne n punctures.
    W 44 ccto %4 or5 %4
    PC ------ -- ------------
    0 725 80. 0 10




    Squares picked in field May 28 to
    22, 1902-----------------------105 56 62.9 33 37.1 4 43.8 16 15.2
    Total.------12-5 850 13510-23



    Average percentage ................ ..... 84.2- ....------1.4---------. 9.7-.....-8.

    A few obvious conclusions may well be stated here. Throughout
    0n 40 (D^, C6 a)^ ^ SS P S









    the season from one-fifth to one-sixth of the squares injured were
    (D-4
    Squares inftroyed by feeding punctures alone. Within this small portion laboratory





    must be included most of the work of males and also of newly
    emerged females before they reach sexual maturity. As the weevil
    injury overtakes the production of squares it becomes increasingly
    difficult for females to find clean squares, and they are forced to19 3.8 24 3.8 110 17.5
    quardeposit eggs in field squares already injured and also to feed upon squares28 to
    June, 1903...--- ----------------. 5W0 3171 19. 25 83 20.75 50 10.0 110 20.0 -






    Squwhich already contain eggs. These conditions serve to increase mostto
    2112,1902 ------------------------.---- 1065 561 62.9 33 37.1 46 43.8 16 15.21
    T otal. -------------------------- 1,235 850 -------- 135 -------- 120 -----.. 236 --------
    A average percentage ---------.---.-- L. .. .. .. 84.2 .----- 13.4 -----... 9.7 ------ 18.3I

    A few obvious conclusions may well be stated here. Throughout




    therapidly the prom portion e-fifth to onf squares containing both egg anjud feeding
    destroyed by feeding punctures. This is still further emphasized byWi thise fact that in June
    mustonly 30 per centd m of hall njured squares contained feeding punctureswly
    emerged females before they reach sexual maturity. As the weevil




    whie in September nearly 60 per cent had been thus injureasid. Whengly
    difficult for females have acces to fian abundcleance of squares,nd they arewill deposito
    deposit eggs in squares already injured and also to feed upon squares



    whicmore than one egg only in eggs. about one-fifth of thoserve in which they ovi-st
    raposit, while idly the proportion of thsquares containing both egg and feeding
    punctures. This is still smallefurther emphasized by the fact that in June
    Thonly 30 per cents to keep egg an d feeding punctures separate, as well
    as to din Seposit only nearly egg in a square, serve thuso produce the greatest




    injury of which the weevils are capable for two obvious reasons: First,
    because wherave several eggs are placed in one square is, they will deposithe
    mcase that more gthan only in about one-fifth olops. If two or more in which they ovi-n a
    posquareit, wone is likely to destroy of those others when bother feeding brings
    punctures is still smaller. A



    them togendencies to keep egg and feeding punctures separritate, as themll
    as to deposit only one egg in a square, serve to produce the greatest



    injury of which thave beevilsn found in thcapable for actual death struggle. Second,
    becashould eggs be placed in squares wh placed in one square it is rarely the
    ease that more than one larva develops. If two or more hatch in a
    square, one is likely to destroy the others when their feeding brings
    them together. They bite savagely at anything which irritates them,
    and larvre have been found in the actual death struggle. Second,
    should eggs be placed in squares which already contained a partly
    grown larva, those hatching would likely find the quality of the food
    so poor that they would soon die without having made much growth.
    One egg will insure the destruction of the square, and a number of
    eggs, could all the larvae live, would do no more. Therefore it is
    plain that the possible number of offspring of a single female is






    I63


    increased directly iii proportion toL the i0ll-lIr ol' h1141r ggs th.at she
    places o e0 ilii sqluaret, alid favorable food conditions for till. lariva
    are best imailltailed by aLvowiding feeding upon squares in which eggs
    have been dleosited, and also by refraining fromn ovipositing ini squuares
    which have been n11uch fedl uponl). These habits of selEctioiIns are,
    therefore, of thelio greatest iimportanic- in the reproduction of the wtevil,
    since they insurt lheli most favorable conditions for tlhe maturity of
    the largest possible number of offspring. In other words, these Iablits
    enable the weevil to do the greatest damage of which it is capable
    while the cotton crop is "making."
    These habits are perhaps less strongly marked in thle case of bolls,
    though still plainly manifested. Feeding and oviposition are (omImnion
    in the same boll, but unless the infestation is very great indeed it
    appears that only rarely is more than one egg placed in one lock,
    though several are often deposited in the same boll. The number de-
    posited depends considerably upon the size of the boll. The smallest,
    which have just set, receive but one, as do the squares, and these fall
    and produce the adult weevil at about the same period as in the case
    of squares. Bolls which are larger when they become infested are
    often found to be thickly punctured and sometimes contain 6 or 8
    larvae. The weevil seems to know when the food supply is sufficient
    to support a number of larvae and deposits eggs accordingly.

    ACTIVITY OF WEEVILS IN DIFFERENT PARTS OF THE DAY.
    The 5 females used in these tests were kept in a field cage on pre-
    viously uninfested plants, and examinations of their work were made
    mostly at four-hour intervals from 6 a. min. to 6 p. min. The exact work
    found was recorded upon tags attached to the squares themselves.
    Temperature readings were taken at the same time as the observa-
    tions. The results are most clearly presented in tabular form (p. 64).




    pr .7 .... .......-


    64

    TABLE XVI.-Activity of five weevils in different parts of the day.


    Date.





    19S3.
    Sept. 2 .....
    Sept. 2-3..
    Sept. 3-.....
    Do .....
    Do.-....
    Sept. 3-4..



    Sept.4.....
    Do.....
    Do.----
    Sept.4-5..


    Period.


    2.:30 to 6 p. mi u-
    6 p.m. to6 a. inm.......---
    6.15 to 10.15 a. min-....
    10.40 a. mn. to 2.40 p. m.in
    3to 6.30p.mn .........
    6.30p.nm.to6a.nm ..


    6.30 to 10 a.in ....-...
    10a.m. to4 p.m -.....
    4 to6p.in -------
    6 p. mn. to 9a. n- ---...


    Tem-
    pera-
    ture.




    oF
    93-80
    80-69
    69--5

    K5-95
    95-84
    84-68


    68-83
    8:3-91
    91-82
    82-79


    Total


    16
    CO





    3
    012







    18
    12
    030
    0




    16
    3
    12
    18
    12
    3


    to






    15
    10
    boD






    10







    15
    11
    1i


    V4-4 5
    o
    P
    .*-I
    ro ..




    l)OB
    0





    10


    2

    6
    3


    4 1! 4
    2 19 12
    11 8 5
    5 0 6



    108 81 60


    SCondition of
    weevil at end
    of period.



    i|

    Placed on fresh
    plant.
    All resting-------
    All active -------
    ----. do .-...- ......
    Placed on fresh
    plant.
    All resting.......


    3 moving to ad-
    jacent squares.
    All active.-------
    All quiet---------
    All feeding ...--


    Remarks.


    Punctures black
    at 6 a. m.
    3 trying to escape;
    cage moved.
    Cage moved.

    Feeding punc-
    tures all Mack;
    small square
    flared.



    Cloudy; every
    we evil on same
    square as at 6
    p.m.


    An examination of these figures shows that weevil activity began
    and ceased at about 75 F. Activity increased as the temperature
    rose, and its maximum coincided with the maximum of daily tern-
    q
    FAHREN TIME
    HEIT 2P IAM 2 3 4 5 6 7 8 9 10 II ?M IPPm 2 3 4 5 6 7 8 9 10 11 12P

    100 -- -
    950 --..... -




    800i


    6o I -


    6 0 .- -IF-


    FIG. 3.-Diagram showing average activity of five female weevils. (Original.)
    peratur-e. It then decreased with the falling temperature until it

    ceased entirely some time during the evening, probably at about
    750 F. See fig. 3. Feeding continued at lower temperatures than

    oviposition, as is known to be the case during the late fall.
    Examinations made in the field between 6 and 7 a. m. on Septem-
    ber 4 showed that all weevils, both males and females, were quietly
    resting at that time with the temperature at about 70O F. On cloudy
    days the activity is less than it is on clear days.






    B u l ,-4 I .I L r,'. r,.P ,, I I ., I.'"I' A -" ,, -- X


    FIG. 43.-THREE LARGE LARVAE IN A BOLL, TWO-THIRDS NATURAL SIZE. ORIGINALL).


    FIG. 44.-FOUR PUPAL CELLS FROM BOLLS (ON LEFT' COMPARED WITH FOUR COTTON
    SEEDS (ON RIGHT", NATURAL SIZE. (ORIGINAL.)


    PLAIF XI.









    B u: rL r, 1 U ",'. U '.. r f A ..L, ..


    TESTING DEVICES. FALLEN AND HANGING INFESTED SQUARES.
    Fig. 4. Device ii-cd( to test attraction ,f molasses in the litlil in theL .spriTig: lig. i,. fillli't squares
    oin gromil in tit-.i:; ti.r. 47, iiit.-It.-ld squares dried and still lIlring iinn 11111i Ih plant: lii.I. I device
    1i-0l 10 itst relative attractiveness to \v Wkvil, ,df American iinIl Egypthinq -uiI,;ir.-. Uriin';il.)


    PL .,t 7 Xll.









    65


    'IAA 'E (1,' I,'<;<; 11,:1' TIMI location of t egg )pill('tlr's, while variable, still sNlJW si,,n.
    selection it'l pLart o01 11 weevil. This mity heI deja liartly toIII llI(-
    form of tli1e squares and partly also to t1he size of 111 we4-vil, blt,1 w haLt-
    ever t e explanation tihe fact remains Iidt, i aL -1Uajority ol(f O a.IsEs..1 le
    egg jpiuncture is imade oti a lilt( abliout hIalIwaIy lbetwweeIi tel, base ;iid
    ti[) of the square. Whe'l so placedI the. egg (,c (-eIl(,s 14 rls'. eiIllnEr jU.St
    inside theI base of a petal or among tihe lowest atiliers i i lle sqI ,ar,,
    according to the varying thickness of the floral coverings at tlliat
    point ('1. I, fig. 3). I'unct.ures are very rarely made below tilis line,
    though they are sometimes made nearer tihe tip). Almost, ilvariably
    the egY puinciture is started through the calyx in preferen i le to i lie
    more tender porftlion of the square, where the corolla only' wnouldl ned
    to be punctured. The reason for the choice of this location 1ay 11e
    found under the subject of the "Relation of warts to ovipositioln," on
    page :9.
    With bolls no selection of any particular location lias been fomind,
    but eggs seem to be placed in almost any portion. l'1. X, lig. 41,
    shows the egg deposited inside the carpel.

    POSITION OF THE WEEVIL WHILE PUNCTURING( FOR OVIPOSITION.

    While engaged in making egg punctures the favorite position of
    the weevil is with its body parallel to the long axis of the square and
    its head toward the base of the same. The tip of the weevil's body
    is thus brought near the apex of the medium size square. Having
    selected her location, the female takes a firm hold upon the sides of
    the square and completes her puncture while in this position. It may
    be that the position described is especially favorable for obtainin&r a
    firm and even hold, and this may have something to do with tle reg-
    ularity with which it is assumed. If so, the apparent choice of this
    location for the puncture is only partially explained, since it has been
    often shown that weevils can puncture and oviposit successfully in
    almost any portion of the square except its very tip.
    Undoubtedly there are other reasons than those of mere conven-
    ience which have so im.nressed themselves upon the inherited experi-
    ence of the weevils as to lead them to the choice of this position and
    the consequent location of the punctures and, eggs. Most apparent,
    of these reasons, and probably also most important, is the advantage
    which this location affords in the protection of the egg, and thie young,
    larva developing from it against the attacks of natural enemies as
    well as from the injurious effects of drying and decay.
    This protection is readily explained by several facts. The place
    chosen is through the thickest and toughest portion of the floral
    envelopes through which the anthers can be reached, since the thick-
    est parts of both calyx and corolla are toward their bases. More
    21739-No. 45-04-----5






    66


    important than the thickness of the layers of vegetable matter is the
    character of the tissues through which the puncture passes. Though
    corolla and calyx are both modifications of original leaf tissue, both
    have changed so greatly in form and texture that the resemblance is
    recognized only by those somewhat acquainted with plant structure.
    The corolla, moreover, has changed far more than has the calyx, and
    in becoming so highly specialized its tissue has lost certain powers
    still retained by the green calyx tissue. The particular power referred
    to in this connection is the ability to heal small wounds. Punctures
    made in the corolla must, therefore, remain open, while small punc-
    tures through the calyx will in most cases be healed by the natural
    outgrowth of the tissue, so as to completely fill the wounds in a man-
    ner entirely analogous to the healing of wounds in the bark of a tree.
    The custom of the weevil of sealing up its egg punctures with a mix-
    ture of a mucous substance and excrement is of great advantage and
    assistance to the plant in the healing process. While undoubtedly
    applied primarily as a protection to the egg, it serves to keep the
    punctured tissues from drying and decay, and thus promotes the
    process of repair.
    As a result of the growth thus stimulated in the calyx, the wound
    is perfectly healed in a short time, and, as is the case in the healing
    of the bark of 'trees, here also we find a corky outgrowth projecting
    above the general surface plane. This prominence the writer Jhas
    termed a "wart" (P1. X, fig. 40). The healing is completed even before
    the hatching of the egg takes place, and thus both egg and larva par-
    take of the benefit of its protection.
    It is possible for the puncture to heal without the full development
    of the wart, and it is also possible for eggs to develop successfully
    even when the puncture was made through the corolla alone and no
    wart developed, but in the latter case the chances are rather against
    it. Occasionally warts do develop from feeding punctures which
    were small, but the exact conditions under which this takes place
    have not been determined.

    THE ACT OF OVIPOSITION.
    The general process of making punctures has been described pre-
    viously under the topic of "Food habits" (p. 38), and will there-
    fore not be repeated here. Having completed the formation of the
    egg cavity, the female withdraws her proboscis and turns end for
    end. She depresses the tip of her abdomen and locates therewith the
    opening to the cavity by feeling or scraping around. In a majority
    of cases the opening is readily found, but sometimes it is not. Then
    the female seems often to lose all sense of locality, tut continues
    scraping with the tip of her abdomen. If she is still unsuccessful,
    she turns and continues the search by means of the antenna, just






    67


    as in the preliminary exanainatimni of a square e1 foray lM'gi nililig a
    puncture.
    In maln3' cases females were noticed to actually place 1.1the tip of the
    proboscis within the opening of the cavity without seeming to be
    aware of its proximity. When the cavity has been found again by
    the antennal senses, the female invariably enlarges it before turning
    again to insert the ovipositor. If the search with the antenna (does
    not prove successful, the female will make another puncture in the
    same manner as at first, appearing to know that no egg has yet been
    placed in that square.
    After locating the cavity by the tip of the abdomen, the ovipositor
    is first protruded to the bottom of the cavity, in which it appears to
    be firmly held in position by the two terminal papilla and the power
    of enlarging the terminal portion of the ovipositor. Slighlit contrac-
    tions of the abdomen occur while this insertion is being made. In a
    few moments much stronger contractions may be seen, and often a
    firmer hold is taken with the hind legs as the egg is passed from the
    body, and its movement may be seen as it is forced along within the
    ovipositor and down into the puncture. Only a few seconds are
    required to complete the deposition after the egg enters the opening
    to the cavity. The ovipositor is then withdrawn, and just as the tip
    of it leaves the cavity a quantity of mucilaginous material, usually
    mixed with some solid excrement, is forced into the opening and
    smeared around over the same by means of the tip of the abdomen.
    This seals the egg puncture and the act of oviposition becomes com-
    plete (P1. X, fig. 39).

    TIME REQUIRED TO DEPOSIT AN EGG.

    Observations upon this point were very conveniently made by con-
    fining females upon squares from which the involucres had been
    removed. A plain glass cover allowed accurate observations, which
    were made to the fraction of a minute. The time required to com-
    plete the excavation and the time required to place the egg were the
    two points especially noted.
    The time of making the puncture was noted in 115 instances, and
    this was found to average 51 minutes. The time varied widely, being
    from 1 to 13 minutes; the usual range was from 4 to 8 minutes.
    From the time that the weevil began to puncture till the sealing of
    the cavity the complete act of oviposition required in 103 instances
    an average of slightly over 7 minutes, ranging in time from 3 to 16
    minutes.
    As these observations were made between October 7 and 23, the
    periods given may be slightly longer than they would be in warmer
    weather. However, various observations made in the field in mid-
    summer agree very closely with the averages given.






    68

    H\TE OF OVIPOSITION.
    Since the period of reproductive activity of the boll weevil is so
    long, the rate at which eggs are deposited is a question requiring much
    time for its determination. There have been found great variations
    in the rate at different seasons, and it is clear that oviposition is even
    more strongly influenced by variations in temperature than is feeding.
    The rate sometimes varies unaccountably and very abruptly with the
    same female upon succeeding days. No explanation for this has as
    yet been found. The rate is influenced also by the abundance of
    clean squares which the weevil can find, so that it is greater in the
    early season, as the degree of infestation is approaching its limit, than
    after infestation has reached its maximum.
    Two extended series of observations have been made to determine
    especially the normal average and the maximum ability of the female.

    AVERAGE.
    Taking first 54 females which had gone through hibernation, we
    find that they deposited on the average 24 eggs each daily in the
    laboratory, and 4 females which were followed under field conditions
    for a total of 93 "weevil-days" deposited 489 eggs during that time, or
    at the rate of 51 eggs each per day. Where the rate of activity is so
    great it is probable that the length of the period would be somewhat,
    but not proportionately, shortened. From many observations made
    in the field during the beginning of the squaring season it seems prob-
    able that a rate of 5 eggs a day is not far from the average in the field.
    From 27 females of the first generation a laboratory average rate of
    -,6 egs each daily was obtained. Five females of this generation
    confined in a cage in the field during the latter part of August for a
    total of 70 weevil days" deposited an average of 6L eggs per day.
    This latter rate is far beyond the actual average rate in the field at
    that period because of the fact that the weevils can not at that time
    find enough uninfested squares to lead then to deposit so many eggs,
    but the possibility remains if only squares enough are present.
    A few words must be said in further explanation of the differences
    which appear between thle field and laboratory results. In the case
    of the laboratory figures the entire oviposition period of each weevil
    and the entire number of eggs deposited are taken into the account.
    As there is a gradual increase in the rate of production of eggs after
    the beginning of deposition and a gradual decrease from the middle
    of the period to its end, the general average is much lower than would
    be that taken at the time of maximum activity. In the case of the
    field figures a short period only is covered, and all conditions of square
    supply were such as to stimulate the weevil to its greatest possible
    activity.







    ( 9


    MAXIMIMM.
    lei diail 41). obse"nv'1atiois madel' ulJIo lHI weev'ils i 1ei, lIaboi,'toy
    1Upl)l)13 a vast InIIII el.'r' of obsev) 4 l 'atioII iS 'rtns f l wlIi(hll tII se .le., 1,axi,\1111111
    figui'res. It lias 1beeni showll Il tha1t uld1111 fav'orwalll<' condlitdiols we.v'ils
    may hie' qxpec(d'ul to )' 11i1ce al average' o)'f I, eggs a (ly f('or a 'Sid-
    e'rall' p'eriO fi "d 1 iI11. It is 11)1 surprising, t1lenfCore, Iitl s ,11. i tIlie
    mai11ximlluill iguI'r es ob1takined! an', vry nmuc'lh l Iarger tl0 all tlat 1, nu ber1-..
    A few instances only will lbe taken froi'i ainIII IlliroisaINls of ';tily

    Trlhe higiest record of e.s deposit ed shows that, 2 sii all fi'imii;(s
    deposited together. 108 ES .,ts iln ; each. This record was iiade( on tliei 7th, sth, and te M of .11e, 1!)11i3.

    TA.i.E XVII.-M3.Iimi titi rft' ,.f orijm.mif ilt.

    Nuinler Days in- Total Number DNys in- Ttal i
    eof .luded egg dt'e- Av'erage of luded .ggs dv- AVLg
    females. iunperiod. posited. P a females, inperiod posited. IL..
    I I
    213 ]IS 18.0 2 2 4:3 h i.s
    1 5 76 15.2 1 3 :0l lii. 1
    25 160 1ti.0 2 5 114 11.4
    5 1 55 11.1) 3 2 54 1
    2 2 47 11. 5 1 42 .4
    12 16 446 13..5 13 13 2x3 9,. 5


    STIMULATING EFFECT OF ABUNDANCE OF SQUARES UPON E(G(G
    DEPOSITION.

    Four actively laying females were confined together upon a few
    squares from September 22 till October 14, 1902, and during this
    period they laid a total of 227 eggs, or an average of 2.3 47 eggs. per
    weevil per day. For the next 13 days these same weevils were isolated
    and supplied with an abundance of squares. )During this slAurter
    period they laid 236 eggs, or 4.54 eggs per female daily.
    Taking equal periods as near together as possible and1 using these
    same weevils, there were deposited in 13 days uponI a few slquares
    144 eggs, or -2.74 eggs per female daily, while during thle (following 13
    days, with an abundance of squares, they each deposited 4.5,4 eggs
    a day.
    These figures are the more striking because the stitnulation was
    plainly shown in spite of the general tendency to lay fewer eggs as the
    weevils grow older and as the average temperature becomes lower.

    RELATION OF WARTS TO OVIPOSITION.

    When the general relation of the warts to tlhe formation of egg,
    punctures was first recognized, an investigation was undertaken to
    determine, if possible, in what proportion of cases the warts could be
    traced directly to egg, or feeding punctures. For this purpose a large
    number of squares, most of which had warts, was picked from l)lants






    70


    in the field and carefully examined in the laboratory. Notes were
    made especially upon the following points: The number of warts, the
    number of punctures obviously made for feeding only, the number
    of special egg punctures, and the numbers of eggs, larvae, and pupm
    found. Only those excrescences were counted as warts which showed
    a positive elevation, and, as was expected, many eggs were found
    which had not been deposited long enough for a wart to have formed.
    Out of the 105 squares examined, 26 showed no warts, while the
    remaining 79 squares had 92 warts. In tracing the connection of
    these 92 warts it was found that 77 at least, or almost 84 per cent of
    the total, resulted from egg punctures. The other 15 warts, or 16 per
    cent, were assigned to feeding punctures, though some of these may
    possibly have been egg punctures in which decay had concealed all
    trace of the eggs or small larvme. One-half of the eggs found were
    in punctures closed by developed warts, and it is likely that most of
    the other half were of too recent deposition for warts to have formed.
    Three-fourths of the larvae found in this lot were in punctures which
    had been overgrown by warts.
    In another series of 35 older squares, 38 warts and 32 eggs, larve,
    and pupe were found. This series also shows that at least 84 per cent
    of the warts resulted from egg punctures. The conclusion seems jus-
    tified, therefore, that warts may be considered as the most conspicu-
    ous external indication of the presence of the weevil in some stage
    within the square.
    It should be noted in connection with warts that feeding frequently,
    and oviposition more rarely, is followed by a peculiar gelatinization of
    the injured portion of the square. This condition spreads, and the
    change produces a considerable internal pressure, so that the square
    becomes distorted and bulges, especially at the place where the punc-
    ture was made. The bulging portion often resembles somewhat a
    wart formation, but its real nature is very different. In many cases
    the gelatinized condition appears to have caused the death of the
    young larvae, either by the pressure or by the abnormal condition of
    the food supply. In a large number of cases, however, this condi-
    tion undoubtedly results from what were feeding injuries only.

    EFFECTS OF OVIPOSITION UPON SQUARES.
    The method of recording the progress of injury to each square, as
    was done in the field cages, has furnished much data upon a number
    of important points. Among these the two of most importance are,
    in order of their occurrence, the flaring and the falling of the square.

    FLARING.
    The flaring of squares (P1. X, fig. 42) is one of the most apparent
    signs of weevil presence, although by no means an invariable accom-
    paniment, as it is usually thought to be. Squares flare in nearly as








    l rge it p)rol)rtimin (of ( Lses frm)IIn adult, feeding i. j1iry taloNe aIts froml
    larval injury within. Any iilijury se'v&ere eouII)igIhI to C ti)aIM 1e 1P falling
    of the square is as liable toI (a1Iset flaring as is t.i1- larvua of the1 we.'vil.
    Flaring results from ani unhealthy condition, whatever Inay IM. the
    cause, and is tfr'eqluently to l) e see ill sqatLres which aWre aboUi)iLt to 1)e
    shed, though tlitwy haV'e never been injured by aLny inuset. i however,
    flaring litas co)e t.o be popullarly assOCiatted with weevil i1nj.J1Nry, a1nld
    must therefore be quite fully considered.
    WXhen resulting from weevil injury, flaring (does not begill, as a Irule,
    immInlediately after thIe injury, bu)t only within from oine to three days
    of the time whlien the square will be ready to fall. In especially
    severe eases of feeding injury, flaring often results in less than twentty-
    four hours. Occasionally the growth of the square overcomes the
    injury from feeding and the involucre, after having flared, again
    closes Iup) and the square continues its normal development as though
    uninjured, and forms a perfect boll. More frequently the square
    gradually loses its healthy green, becoming a sickly yellow in color,
    and falls in a short time.
    WVhen injured by the feeding of a young larva as the direct result
    of successful oviposition, flaring has been found in an average of 139
    cases to take place in almost exactly 7 days from the deposition of
    the egg. These observations cover the season from June to Septem-
    ber, when the developmental period averages about 19 days. Fully
    one-third of the weevil's full development has, therefore, taken place
    before flaring results.
    FALLING.
    Squares which flare because of injury from larval feeding within
    always fall, except the small percentage which, though entirely cut
    off from all vital connection with the plant, still remain hanging
    thereon by a small strip of bark and gradually become dry and brown
    upon the plant. Falling is but the natural final consequence of injury
    or disease (PI. XII, fig. 46). Whatever its cause, it is brought
    about in exactly the same way as the shedding of leaves by the plant
    in the fall, by the formation of an absciss layer of corky tissue cutting
    off the fibro-vascular bundles supplying nourishment to the square.
    The exact location of the cork area is to be seen at the scar left by
    every fallen square.
    In 539 cases definitely noted between June and September, 1903,
    the average time from egg deposition to the falling of the square was
    9.6 days. For this same period full development required an average
    of 19 days, so that falling occurred at the middle point in the weevil's
    development. From a comparison of the time of flaring with that of
    falling it is seen that the interval between these two points averages
    about 2.5 days. In late fall the time between oviposition and falling,
    as recorded in 21 cases, was found to be about 16 days.






    72


    PERIOD OF OVIPOSITION.
    With the exception of hibernated weevils, it appears that oviposi-
    tion begins with most females within a week after they begin to feed
    and continues uninterruptedly until shortly before death. While
    females frequently deposit their last eggs during the last day of their
    life, a period of a few days usually intervenes between the cessation
    of oviposition and death.
    In the case of 52 hibernated females the actual period of oviposition
    averaged about 48 days, the maximum being fully 92 days.
    In an average made with 21 females of the first generation the
    actual period was almost 75 days, the maximum period being 113 days.
    The average period for the females of the first two generations
    appears to be longer than that for any other. In the third generation
    the average period for 11 females was 58 days, the maximum being 99
    days, and in the fifth generation for 5 females the period averaged 48
    days, with the maximum only 62.
    The approach of cold weather cuts short the activity of the weevils,
    which become adult after the middle of August, thereby decreasing
    the length of their oviposition period. Weevils which pass through
    the winter actually live longest, but as it must take more or less vital-
    ity to pass through the long hibernation period their activity in the
    spring is thereby lessened.
    The weighted, average period of oviposition of the 89 females here
    mentioned is 55.6 days.
    DOES PARTHENOGENESIS OCCUR?
    To test the possibility of weevils reproducing parthenogenetically,
    12 individuals were isolated from the very beginning of their adult
    life. Each beetle was supplied daily with fresh, clean squares and
    careful watch was kept for eggs. The first noticeable point was that
    no eggs were found till the weevils were about twice as old as females
    usually are when they deposit their first eggs. After they began to
    oviposit, it was found that a very small proportion of the eggs were
    deposited in the usual manner within sealed cavities in the squares,
    but nearly all of them had been left on the surface, usually near to
    the opening to an empty egg puncture. This same habit was shown
    by a number of females, and so can not be ascribed to the possible
    physical weakness of the individuals tested. The number of eggs
    deposited was unusually small, and those few placed in sealed cavities
    failed to hatch. After somewhat more than a month had been passed
    in isolation, one pair was mated to see if .any change in the manner of
    oviposition would result. The very next eggs deposited by this fer-
    tilized female were placed in the square and the cavity sealed up in
    the usual manner, showing that her infertile condition had been the
    cause of her al)normal manner of oviposition.
    A Illu(.h more extensive series of experiments along this line is
    (',-sir






    7":


    DEVELOPMENT.

    PERCENTAGE OF WEEVILS DEVELOPED FROM INFESTED
    SQUARES.

    During the season of 19!01)2 part o(r tlhe iniy L"squarles r' gatleredI inll
    infested fields for the blreeding of weevils were folhlow(e lI to learn somll-
    thing of the percentage which produced C normal al1dults. No exani-
    nation was 1111ado0 for those not yielding a weevil. I'le dlec;y .f W
    square during the period from its falling to tihe Il xilullllt tile l llat
    must be allowed for weevils to eseapje normally so obliterates aly
    small amount of work by a larva that it is difficult even with exaimi-
    nation to determine accurately the number of dead small lrva'.

    TABLE XVIII.-Pe'reen htge of weeriln frot' ijfgi.ft .1r',.

    Penefiii
    Number Numilr iageU of
    Locality. Approximate d(il0 of of s.uiar.s
    .i sejari.,. w -vvils. prolucving
    | w .vils.

    19(t2.
    Victoria, Tex --------- ------------------- July to August....... 1,125 :. 2.;
    Guadalupe, Tex ------------------------- August -------- :t li8 2H. )
    S1903.
    Victoria, Tex ----------... ---.............-------....------. I June- .. 334 1 vi 32.0
    Do....----------....-------. ---------------- June to August ...... 873 1 :'U 41.0
    Do--...--...---------------------------------........................... August to September :36 192 C.O0
    Total. ----------------------- -------- .... 3,1l7 1,121 :i. 3


    It seems safe to conclude that throughout the season fully one-third
    of the squares which fall after receiving weevil injury may be expected
    to produce weevils.

    DEVELOPMENT OF WEEVILS IN SQUARES WHICH NEVER FALL.

    It is generally true that squares seriously injured by th.e weevil
    sooner or later fall to the ground. Some plants, however, slied tlie
    injured squares more readily than do others. It seems 1t1 be a mat-
    ter of individual variation rather than a varietal character. Thus
    occasional plants retain a large proportion of their infested squares,
    which hang by the very tip of the base of the stemin. Normally the
    squares are shed because of the formation of an absciss layer of corky
    tissue across their junction with the stem. In the case of tlie slquares
    which remain hanging the fornimation of this layer seems to be incom-
    plete, or else it becomes formed in an unusual plane, so that while the
    square is effectually cut off, it merely falls over andl hangs by a bit of
    bark at its tip (Pl. XII, fig. 47). In this position it dries thoroughly
    and becomes of a dark-brown color. Plants showing 6 or S of these
    dried brown squares are quite common in infested fields. Although
    exposed to complete drying and the direct rays of the sun, the larvu
    within are not all destroyed. This peculiarity rminls one strongly
    of the European Anthonoomus p)morumin the work of which in caus-






    74


    ing apple buds to hang dead upon the trees has caused the common
    name of "Brenner" to be applied to it.
    At intervals during the summer of 1903 such dried squares and
    small dried bolls were picked for careful examination in the labora-
    tory, the condition of 342 being recorded, with the following results:
    Adults present 2, escaped 23; pupae alive 29, dead 2; larvaB alive 85,
    dead 47; parasites present 44, escaped 6. Sixty-three squares which
    failed to show weevil work and 42 small dried bolls from which the
    corollas had fallen were probably destroyed largely by the feeding of
    the weevils. Taking the total number of squares and bolls examined
    as the basis of computation, it appears that 69.3 per cent of them
    showed weevils present in some stage. Of the immature stages, 30
    per cent were dead, 14.6 per cent having been parasitized. It seems
    a conservative estimate therefore to say that fully one-third of these
    exposed dried squares may be expected to produce adults. Consider-
    ing the exposed condition of such squares this seems to be a very
    high percentage.
    The season of 1903 was not as hot at Victoria as was that of 1902,
    and the lower temperature prevailing may have favored the develop-
    ment of a larger proportion of the weevils in these squares than would
    normally emerge. The maximum temperature reached in 1902 was
    104.3 F., while in 1903 the maximum was only 97.5 F. No examina-
    tions of this subject were made in 1902, and therefore no positive
    comparisons can be drawn. The observations made, however, cer-
    tainly show that a complete drying of the square does not necessarily
    destroy the larva, and that a square may undergo far more exposure
    to direct sunshine than had been supposed possible without causing
    the death of the larva or pupa within.

    LENGTH OF THE LIFE CYCLE.
    This question has been studied carefully, both in the laboratory
    and in the field. Most of the observations made in 1902 were in the
    laboratory, while those of 1903 were in the field.
    In the laboratory uninfested squares were exposed to active weevils
    for oviposition, and the supply of clean squares was renewed each
    day. The beginning of the cycle was this known to within a few
    hours. The squares with eggs were carefully kept and the date of
    emergence of each adult was then noted. To the period thus found
    must be added the time intervening between the leaving of the square
    and the deposition of the first eggs. This gives the length of the life
    cycle. The material upon which these observations were made was
    necessarily other than that used in determining the length of the
    various stages. The period in bolls is far different from that in
    squares. The figures here given refer to squares.