The bean thrips

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Title:
The bean thrips
Series Title:
Bulletin / U.S. Dept. of Agriculture. Bureau of Entomology ;
Physical Description:
49 p. : ill. ; 23 cm.
Language:
English
Creator:
Russell, H. M
Publisher:
Govt. Printing Office
Place of Publication:
Washington, D.C.
Publication Date:

Subjects

Subjects / Keywords:
Bean thrips -- Life cycles   ( lcsh )
Bean thrips -- Control   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 44-45) and index.
Statement of Responsibility:
by H.M. Russell.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 021640089
oclc - 62123818
System ID:
AA00018859:00001

Full Text
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U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY-BULLETIN No. 118.
L. 0. HOWARD. Entomologist and Chief f Bureau.


THE


BEAN THRIPS.


BY


H. M. RUSSELL,
Entomological Assistant.
I


ISSUED OCTOBER 16, 1912.


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1912.























BUREAU OF ENTOMOLOGY.

L. 0. HOWARD, Entomologist and Chief of Bureau.
C. L. MARLATT. Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Executive Assistant.
W. F. TASTET, Chief Clerk.

F. H. CHITTENDEN, in charge of truck crop and stored product insect investigations.
A. D. HOPKINS, in charge of forest insect investigations.
W. D. HUNTER, illn. charge of southern field crop insect investigations.
F. M. WEBSTER, inl charge of cereal and forage insect investigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILLIPS, in charge of bee culture. i
D. M. ROGERS, in charge of preventing spread of moths, field work.
ROLLA P. CURRIE, in charge of editorial work.
MABEL COLCORD, in charge of library..

TRUCK CROP AND STORED PRODUCT INSECT INVESTIGATIONS.

F. H. CHITTENDEN, inl charge.

H. M. RUSSELL, C. H. POPENOE, WM. B. PARKER, H. 0. MARSII, M.. H. HIGH,
FRED A. JOHNSTON, JOHN E. GRAY, entomological assistants.
I. J. CONDIT, collaborator in California.
W. N. ORD, collaborator in Oregon.
THOMAS H. JONES, collaborator in Porto Rico.
MARION T. VAN HORN, PAULINE M.I. JOHNSTON, ANITA M. BALLINOEB, preparators.
2












ADDITIONAL COPIES of this publication
may be procured from the SurzmNTmm-.
ENT or DOCUMmNTs, Government Printing .y
Office, Washington, D. C., at 10 cents per copy l

j4

















LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY,
Washington, D. C., April 24, 1912.
SIR: I have the honor to transmit herewith for publication a manu-
script entitled The Bean Thrips," by H. M. Russell, an entomo-
logical assistant of this bureau.
This bulletin deals with an insect pest of the family Thripidue,
the study of which has been hitherto largely neglected, and which of
recent years has attracted considerable attention from an economic
standpoint, as the cause of immense losses in the Pacific coast regions
and elsewhere to truck farmers. The insect is closely related to the
tobacco thrips, as well as to the onion thrips, to which species are
chargeable untold losses in the production of these two staples. Ex-
periments to produce formula and devices with which successfully
to combat this insect are being perfected, and methods for the com-
plete control of the pest are early expected.
I recommend the publication of this manuscript as Bulletin No.
118 of this bureau.
Respectfully, L. 0. HOWARD,
Chief of Bureau.
lion. JAMES WILSON,
Secretary of Agriculture.




















CONTENTS.


Introduction. . ......................
Nature and extent of injury .............
Description ............................
The adult female ...................
The adult male ....................
Recently emerged adults..........
The egg ...........................
The first-stage larva ................
The second-stage larva..............
The young nymph or prepupa......
The full-grown nymph or pupa.......


Origin and distribution........................
H history .......................................
Recent records ...............................
Habits of the adult ............................
Method of mating.........................
Method and time of oviposition ............
Number of eggs and period of oviposition .
Proportion of the sexes ....................
Kinds of reproduction .....................
Feeding habits .............................
Flight ....................................
Leaping ..................................
Normal length of life .......................
Length of life in winter ...................
Habits of the larva ............................
H atching..................................
M olting..................................
Habits of the prepupa and pupa .................
Food plants ...................................
B eans ....................................
Other vegetables.........................
Pear ......................................
Alfalfa ...................................
Cotton ...................................
W ild plants..............................
Seasonal history at Compton, Cal..............
The egg ..................................
The larva ..................... ..............
The prepupa and pupa.....................
Total life cycle ...........................
Emergence from hibernation...............
Entrance into hibernation..............
Number of generations....................


Page.
7
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37


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. . . . . . .


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




THE BEAN THRIPS.

PacP. .i
Seasonal history in the Imperial Valley........................................ .7
Egg period .......................................................... 37
Larval period............ ............................ ............ 38 .
Prepupal and pupal periods ........................................... 38
Seasonal history at Tempe, Ariz.......................................... 3) .-
Hibernation. ............................................................ 39
Notes on occurrence...................................................... 40
Natural control ........................................................... 40
Rains ..... ........................................................ 40
Natural enemies. .................. ................. 41 ,
Artificial control .......................................................... 42
Cultural m ethods .................................................... 42
Spraying ..........................................................43
Distributing the parasites ............................................ 44
Bibliography ............................................................. 44 ,
Index .................................................................... 47





ILLUSTRATIONS. I

Page.
FIG. 1. Side view of the head of a thrips, showing the mouthparts .......... 8 i
2. The bean thrips (Heliothripsfasciatus): Adult female and details...... 9
3. The bean thrips: Eggs ............................................. 10 i
4. The bean thrips: First-stage larva................................. 11
5. The bean thrips: Second-stage larva-............................... 12
6. The bean thrips: Prepupa ....................................... 12
7. The bean thrips: Pupa ........................................ 13
8. Map showing present known distribution of the bean thrips (Heliothrips 8
fasciatus) ...................................................... 15 "
9. Alfalfa showing injury by the bean thrips.......................... 29 i
10. The bean thrips: Prepupae parasitized by Thripoctenus russelli....... 41'
11. A hymenopterous parasite, Thripoctenus russelli: Adult .............. 42


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THE BEAN THRIPS.
(Heliothrips fasciatus Pergande.)


INTRODUCTION.
In the State of California during the past four or five years the
bean thrips has been reported with increasing frequency as a serious
pest to various crops. The common name bean thrips is somewhat
of a misnomer, as this insect feeds on many different crops, but is re-
tained here, as it is well known by that name in California. That
State, with its long, dry summer, furnishes climatic conditions un-
usually favorable to the development of thrips, and several species
have gained such a foothold there as annually to cause a loss of hun-
dreds of thousands of dollars.
In the summer of 1909, Mr. R. S. Woglum, of the Bureau of En-
tomology, informed the author that during the summer before he had
seen hundreds of acres of beans in southern California so seriously
infested by the bean thrips that they had the appearance of plants
scorched by fire; and as this thrips seemed to be increasing in num-
bers and destructiveness it appeared to be the part of wisdom to
obtain all possible information concerning its life history and control
before it reached the enormous abundance of the destructive pear
thrips (Euthrips pyri Daniel). When, therefore, the Bureau of
Entomology established a field station at Compton, Cal., in Septem-
ber, 1909, for the study of truck-crop and sugar-beet insects, the
writer planned, among other projects, to undertake as complete a
study of this insect as time would permit. With this in mind, the
bean thrips has been the subject of thorough investigation during the
years 1910 and 1911. During this time, however, the insect was not
again so destructive to beans, so that remedies with spray mixtures
could not be thoroughly tested. Nevertheless, as the life history has
been worked out and a large fund of information obtained on the dis-
tribution and habits of this thrips, together with knowledge of a
natural enemy of some promise, this paper is published at the present
time.
At Compton, in Los Angeles County, where the life history of this
insect was studied by the writer, the temperature is quite cool. since
the location is near the coast.




THE BEAN THRIPS.


In the Imperial Valley the life history of the bean thrips and its j
injuries to alfalfa and cotton have been investigated by Mr. V. L.
Wildermuth, of this bureau, and where his observations are used...
credit is given in the text.1 Use has been made of observations, H
by Messrs. P. R. Jones and S. W. Foster, of this bureau, on this insect
in the more northern points in the State. Since July, 1911. the writer
has been ably assisted by Mr. John E. Graf. He also wishes to ex-
press his appreciation to Dr. F. II. Chittenden, under whose direc-
tions he has conducted the investigation, and to Prof. F. M. Webster
for the free use of notes obtained by his agents.
NATURE AND EXTENT OF INJURY.
The damage caused by the bean thrips is not confined to the foliage,
but affects as well the fruit and stems of the plant attacked. The
injury is caused by the method of feeding.
Both young and adults obtain their food by
S puncturing the leaf tissue with their sharp
Smouthparts and, after lacerating it, with-
drawing the plant juices at the point of
.\ ^attack. Figure 1, although a drawing of a
--^^''' .different species, gives an idea of the mouth-
1 parts of this insect.
U Each time as the contents of the leaf at
-the point attacked are removed, the thrips
3 moves to a new point and repeats the opera-
ytion, so that if the insects are abundant or
the attack is long continued the leaf tissue is
Fio. 1.-Side view of the
i.cad of a thrips, showing destroyed over the entire surface. As the
the mouthparts. Much en- supply on one side of the leaf is exhausted
large. (After Moulton.) r_ .
large. (fter Moulton.) the larvw move around to the other, or if
adults are present these fly or jump to more tender leaves. The
infested and badly injured leaves turn yellowish or white, dry up,
and either drop off or hang lifeless to the plant. Then, as the
attack continues, successive leaves are attacked until in extreme
cases the entire plant is killed.
DESCRIPTION.
HeHioth.rips fasciatus belongs to the Suborder Terebrantia and the
Family Thripidce of the Order Thysanoptera, being placed in this
position because of the downward-curved ovipositor of the female.
The 8-segmented antennae, with the last segment much longer than
the 7th, and the reticulated surface of the body, together with the
pointed spines on the wings, place this insect, in the Genus IHelio-
1Mr. Wildermuth studied the insect in its relation to alfalfa, without knowing that it J:
was being investigated by the author. His studies, made under quite different climatic
conditions, add materially to the value of the results obtained.






DESCRIPTION.


thrips. The habits of the larva are also quite characteristic of this
genus, for the habits of the larvae of the greenhouse thrips (Helio-
thrips hwemorrhoidcalis Bouche) and of Heliothrips rubrocinctus
Giard are almost identical with those of the present species.
THE ADULT FEMALE.
The adult female (fig. 2) is about one-twenty-fourth of an inch
in length (0.9815 nmm. to 1.1174 mm.; average, 1.0405 mmin.) and
about one-fourth as wide as long (0.2265 mm. to 0.2869 mm.; average


IIu. 2.-The bean thrips Heliolhrips fasciatus): a, Adult female; b, ventral side of
abdominal segment of same; c, antenna of same. a, Greatly enlarged; b, c, more
enlarged. I Original. i
width, 0.2529 nmm.) and is fusiformin in shape. The head and body
are black and, under the microscope, are seen to be covered witlh
distinct reticulations and short white hairs. The antennae are 8-
segmented and two and one-half times as long as the head, and are
held out in front of the body. They are black, more or less banded
with white, and bear white hairs. The wings are held folded to-
gether down the middle 6f the dorsum; they are black, crossed by
a white band at the base and a white band at three-fourths the dis-
tance from the base. The wings are fringed with long white hairs.
The legs are black, banded with white.'
For a detailed description of thy genus and the species for use of systematists. see
Hinds's Monograph of the Thysanoptera (Proc. U. S. Nat. Mus., vol. 26, 1902), pp.
174-175.
51097 -Bull. 118-12- 2




10


THE ADULT MALE.
The male resembles to a great extent the female, as the color
and the markings are the same, but it is noticeably smaller in size
and apparently more active. When viewed under the microscope
the sexual organs are seen to be distinctly different, and in light-
colored or cleared specimens the testes may be seen as two orange-red
bodies in the abdomen, and on the middle of each of segments 2 to 6
on the ventral side are yellowish oval spots. The total length of ,|
the male is 0.7097 mm. to 0.8002 mm.; the average, 0.7474. mm. The I
greatest width across the mesothorax is 0.1963 mm. to 0.2114 mm.;
the average, 0.1978 mm....

RECENTLY EMERGED ADULTS.
Both sexes, when just emerged, have the head and thorax a light
yellowish orange, with the eyes and ocelli bright red. The antennae
are white and ringed with brown, while the wings are dusky, crossed :
by bands of a darker color. The legs are i
white, with ends of each segment more or less
black. Gradually the color darkens, and in
a day they all have the fully matured colors,
as described above.

THE EGG.

FIG. 3.-The bean thrips: The egg (fig. 3) is bean shaped, 0.21 to !
Eggs. Greatly enlarged. 0.255 rm. in length and 0.105 to 0.12 mm. in
(Original. i
width, and is very delicate and thin shelled. ,
It is translucent white, with a smooth shining surface. The eggs are
laid in the tissue of the leaf or in the veins, or even in the stems, and
in case of beans may be laid in the pods themselves. As the embryo
within develops, the egg becomes swollen, and the little pocket in
which it is inserted becomes raised above the leaf surface. The eggs
may be seen in the leaf tissue if examined with a hand lens before
the light. Each little egg pocket stands out, because of its lighter
color, and within the crude outline of the egg may be seen.
The younger stages of this insect differ distinctly from those of
Jteliothrips haemorrhoidalis' in the dashes of crimson so generally
present on the sides.
THE FIRST-STAGE LARVA.2
.:!
(Fig. 4.)
Length, 0.42 mm.; width of mesothorax, 0.135 mm. General shape fusiform, i
similar to Heliothrips hwmorrhoidalis; head, antennae, and legs large in propor-
I For description of Hcliothrips hwmorrhoidalis, see "The Greenhouse Thrips," Bul. 64,
Part VI, Bur. Ent., U. S. Dept. Agr.- pp. 46-48, 1909.
P Description made while larva was very young and before feeding commenced.


THE BEAN THRIPS.






DESCRIPTION. 11

tion to rest of the body. Color translucent white. Head large, quadrate; eyes
reddish; ocelli absent. Antennae 0.195 mm. in length, apparently 7-segmented:
basal segment cylindrical, short; second nearly twice as long as first, barrel-
shaped; third and fourth spindle-shaped, ringed with a few fine hairs: fifth.
sixth, and seventh slender, nearly equal in length. Legs translucent white.
Abdomen tapering posteriorly; first eight segments nearly equal in length, last
two segments longer than others; each abdominal segment with longitudinal
rows of setae, the tenth with
four setse about 0.045 am e. in
length.
At this stage there seems to
be nothing to distinguish this
species from H. hiei orrhoidalis.

THE SECOND-STAGE LARVA.

(Fig. 5.)

Length. 1.05 mim.; width of
lnesothorax, 0.27 mm. Shape
fusiform, about same as larva;
of mesothorax and metathorax
long, robust, cylindrical; sides
of mesothorax and metathorax
and first five abdomiinal seg- ..
ments nearly parallel; pro-
thorax narrowed toward head;
last five abdominal segments
tapering to the last segment,
which is cylindrical and trun-
cated at end. Color of head
and prothorax light yellow,
mesothorax and metathorax
and first six segments of abdo-
men translucent white, stained
on sides with crimson blotches
and with yellow on dorsum to
some extent; next three seg-
ments of abdomen the color of
head, last segment of abdomen Fio. 4.-The bean thrips: First-stage larva. Greatly
white; alimentary tract plainly enlarged. (Original.)
indicated by the brownish color
given it by inclosed food. Surface of body covered with minute granulations.
Head quadrate, rounded in front and notched behind the eyes, 0.12 mm. long,
0.0825 ram. wide; eyes small, reddish: ocelli absent. Antennae 7-segmented, first
four segments the color of head, the others translucent white; first segment
short, cylindrical; second longer, barrel-shaped; third and fourth spindle-shaped
and annulated; fifth, sixth, and seventh slender and cylindrical. Legs long,
yellowish. Abdomen 0.60 mm. in length, fusiform, ovipositor not formed; seg-
ments with rows of fine seth increasing in length toward posterior end; ninth
and tenth segments with longer sette.




12 THE BEAN THRIPS.'|

THE YOUNG NYMPH OR PREPUPA. ,

(Fig. 6.)

Length, 1.02 mm.; width of mesothorax, 0.255 mm. Shape fusiform, similar
to adult. Head, length, 0.09 mm.; width at eyes, 0.157 mm. Head translucent
white, vertex slightly yellowish, ocelli absent. Head rounded in front, slightly
notched behind the eyes; eyes red, made up of a few facets, surface faintly
reticulated; two pairs of sete behind the eyes and two pairs between the eyes. &
Antennre translucent white, extending forward, 0.195 mm. in length; segments
indistinct but apparently 7-segmented.
Prothorax about one-half again as wide as long, sides rounded, posterior edge
broadest, semitranslucent white to yellow, posterior angles tinted with crimson,

*ii


FiG. 5.-The bean thrips: Second-
stage larva. Greatly enlarged.
(Original.)


FIG. 6.-The bean thrips: Prepupa.
Greatly enlarged. (Original.)


setie around margin. Mesothorax with rounded angles, translucent white to
faint yellow, sides and posterior angles tinted with crimson, wing-cases trans-
parent white, distinct from each other, those of forewings extending to middle
of second abdominal segment and those of hind wings extending to middle of
third abdominal segment. Legs strong, translucent white.
Abdomen fusiform as in adult, translucent white to faint yellowish, edges
with tint of crimson, which enlarges to fair-sized blotches on sides of seventh
,nd eighth segments; number of longitudinal rows of setae increasing in length
toward posterior end. Length of abdomen, 0.62 mm.






DESCRIPTION.


13


THE FULL-GROWN NYMPH OR PUPA.

(Fig. 7.)
Length, 0.99-1.09 mm.; width at mesothoracic angles, 0.24-0.255 mm. Shape
similar to that of adult. Color orange; posterior border of prothorax,
mesothoracic angles, sides, and abdominal segments 2, 3, 6, and 7 more or less
crimson. Head, length, 0.11 mm.; width, 0.18 mm.; orange, apparently faintly
reticulated; eyes dark red, larger than in prepupal stage, facets small. Three
ocelli present in close triangle between eyes, in color yellow. Antennae laid
backward on head and reaching to beyond middle of prothorax; segments in-
distinct, translucent white;
segments 1 and 2 projecting
in front of the head and 2
with four setae or hairs, two
extending forward, about
0.0135 mam. in length. Tho-
rax light orange or yellow.
Prothorax about twice as
wide a long. Wing-cases
0.54 mim. long, extending to
seventh abdominal segment,
translucent white. t Length
from head to end of wing-
pads, 0.825 mm. Legstrans-
lucent white. Abdomen
fusiform, similar to adult,
surface plainly reticulated
in older specimens, setfe
well developed, the longest
ones at posterior end.
Length of abdomen, 0.612
mm.; width, 0.31 mm.;
length of posterior seta,
0.085 mm.
The younger stages of this
insect differ distinctly from
those of H. hwmorrhoidalis1
in the dashes of crimson so
generally present on the
sides.
The pupa of the male
is shorter and more slen-
der than that of the fe- FIG. 7.-The bean thrips: Pupa. Greatly enlarged.
male. This pupa differs (Original.)
from H. hlemorrhoidalis in its smaller size, in its yellow color, with
the sides of the abdomen more or less stained with crimson, and in
having the hairs of the body longer and the second segment of the
antennae with two long sete.
The foregoing descriptions are for the parts of California in Los
Angeles County and more northern points, for Mr. Wildermuth
2 For description of Heliolhripa htemorrhoidalis, see The Greenhouse Thrips," Bu!. 64.
Part VI, Bur. Ent., U. S. Dept. Agr., pp. 46-48, 1909.





THE BEAN THRIPS.


found that the different stages in the Imperial Valley lacked the red !i
markings except in the cooler weather of the late fall. i
ORIGIN AND DISTRIBUTION.
This insect was first described by Mr. Theodore Pergande from It|
specimens taken in Yuba County, Cal. A few years later he identi-
fled a thrips from Lewiston, Idaho, as this same species.
Mr. Dudley Moulton reported that this species had been collected
in Colusa County by Mr. E. K. Carnes, in Santa Rosa County by
Mr. 0. E. Bremner, and in the Santa Cruz Mountains, Santa Clara
County, by himself. Mr. D. L. Crawford recorded fasciatus from
Santa Paula, Ventura County, Cal., and from Claremont and Chino,
Cal. Mr. William B. Parker, of this bureau, collected it at Davis and
Hamilton City, Cal. Mr. P. R. Jones, engaged in pear thrips in-
vestigations, reports that this insect occurs very commonly around :
Lindsay and San Jose, Cal. Mr. S. W. Foster, while engaged in the
same investigation, collected this insect from Martinez, Cal., and later ,
found it frequently throughout Contra Costa County."
Mr. V. L. Wildermuth, engaged in cereal and forage insect in-
vestigations, has collected this insect in California at Indio, River-
side County, and at Bard, El Centro, and Holtville, Imperial County,
and in Arizona at Yuma, Yuma County, Buckeye and Tempe, Mari-
copa County, and Sacaton, Pinal County.
During the present investigation the writer has collected this insect
quite extensively from many places in southern California. In 1910
it was found to be very abundant on wild lettuce in several yards i
and alleys in the city of Los Angeles itself. At various times it
has been collected from Bell, Compton, Gardena, Glendale, Holly-
wood, Laurel Canyon, Puente, San Gabriel, Sierra Madre, Tropico,
and 1Whittier, in Los Angeles County. In Laurel Canyon the author
found it feeding on wild food plants in uncleared land about 6 miles
from cultivated fields. It was also collected near the entrance of the
canyon, scattered over the mountain sides on various wild plants. At
Sierra Madre it was taken at an elevation of 750 feet.
It was also collected at Garden Grove, Huntington Beach, Smelt-
zer, and Sunset Beach, in Orange County, Cal. While on a trip in
October, 1910, the author found this insect to be generally distributed
throughout the town of Oxnard, and in Montalvo and the entire
outlying sugar-beet district of Ventura County.
In February, 1911, the author made a trip to San Diego to investi- 4
gate the conditions in reference to truck crops there, and in Mission
Valley-a long, narrow, and fertile valley lying to the north of San
Diego, and devoted to truck crops-this insect was fotmund feeding to
some extent on pea vines. The writer left California for Washing--:..
ton, D. C., in September, 1911, and while delayed at Sparks, Nev.,
he examined several clumps of wild lettuce growing along the rail- .-
i


14






ORIGIN AND DISTRIBUTION.


road track and collected both larval and adult forms of the bean
thrips upon this plant.
Mr. A. C. Morgan, of this bureau, recently reported to the writer
that he had collected the species on October 10, 1910, at Clarksville.
Tenn. The fact that this insect is so widely distributed in all parts
of California seems to point strongly to that State as its original
home. This is also strongly supported by the fact that Moulton
collected it from wild vetch in the Santa Cruz Mountains and that
the writer collected it in wild, uncultivated tracts in the mountains
and canyons north of Los Angeles, 5 and 6 miles from cultivated
crops. This point of view is further strengthened, because the au-
thor has found this insect feeding on more than 20 native wild
plants.


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Fau. 8.-Map showing present known distribution of the bean thrips (Ifeliothrips fasciatus).
(Original.)
Mr. J. D. Hood, formerly of the office of the State entomologist
of Illinois, recently informed the writer that he possessed specimens
of this thrips that were collected by Prof. Lawrence Bruner at
Lincoln, Nebr., February 14, 1899, and that he had collected this
same species at Urbana, Ill., in March, 1907. In both cases the
thrips were taken on California oranges and had evidently been car-
ried across the country while hibernating in the navel end of the
fruit. This is an excellent illustration of how this insect may be
distributed through the agency of man.
Although this insect is quite minute and has been little studied,
at the present time it is known to occur through the entire State of
California, in several places in Arizona, in Nevada, and in Idaho
near the Washington State line. It has also been found in one
locality in Tennessee. Figure 8 has been prepared to show the
present definite localities where this insect has been observed.


15





16 THE BEAN THRIPS.

Without doubt this insect occurs over the entire Pacific coast of F:i:
the United States and down into Mexico for some distance and poe- ||
sibly even into Central America. As it becomes better known it
will probably be found to occur in several of the other Western |
States and some of the Eastern States as well.
HISTORY. :
In 1895 Mr. Theodore Pergande (1)1 described this species from one
specimen received from Yuba County, Cal., where it was taken on !
an orange leaf infested with (Aspidiotus) Chrysomphalus aurantii
Mask. At that time he expressed the opinion that the occurrence
on this plant was accidental. In view of our present knowledge,
however, of the feeding habits of this insect, this specimen was
probably feeding on the foliage of the orange itself.
In 1902 Hinds (3) redescribed the female from one specimen in
the collection of the Bureau of Entomology. At that time he wrote
that nothing was known of the life history. ,
Miss Daniels (4), writing in 1904, noted the occurrence of this
thrips in California. At the same time she erected a new genus and
species, Caliothkips woodworthi (4), for the male of Heliothrips
fasciatus. This error was first pointed out by Dudley Moulton (6)
in 1907, and the present writer agrees with him, as the male of
fasc4atus fits the description exactly except in the number of an-
tennal segments. Undoubtedly Miss Daniels made a mistake in the
number of segments inthe antenna, since fasciatus is 8-segmented only.
Crawford (7), in 1909, under "Notes on California Thysanop-
tera," records taking numerous specimens in southern California.
These were captured on pine, Lotus glaber, and apple.
Under the name Euthrips fasciatus, Bremner (8), in 1910, reported
this insect as injuring beans and peas and as occurring on alfalfa
and on peach and pear trees. He recommended spraying with nico-
tine solutions, and wrote that of these sulphate of nicotine in the
proportion of 1 ounce to 5 gallons of water had given perfect
success. :
In 1911 Coit and Packard (9) wrote that the bean thrips caused .
considerable defoliation to cotton and alfalfa in Imperial Valley, Cal.
Moulton (10) also gave a list of its food plants.
The present writer, in 1911 (12) and also in 1912 (13), published
two papers dealing with the life history and habits of Thripoctenus 1.
russelli Crawf., a parasite reared in large numbers from this thrips. .
RECENT RECORDS.
This species, as identified by Mr. Pergande, was sent to the Bureau
of Entomology January 25, 1898, by Mr. M. J. Wessels, of Lewiston, ..
1 Numbers in parentheses refer to the Bibliography, pp. 44-45. ,j





HABITS OF THE ADULT.


Idaho, who collected it in a diseased spot of a crab apple. On August
27, 1908, Mr. I. J. Condit sent in specimens of this thrips from
Davis, Cal., where they were injuring sugar beets. He wrote:
I examined the beets and found them literally covered with thrips, both the
surface and underside of the leaves being badly infested. There were very
few leaves which were not attacked, most of them having the appearance of
the specimens sent. A field of tomatoes near by was also becoming infested.
The lower leaves especially were yellow and some falling off.
Mr. S. W. Foster informed the writer that on August 26, 1909,
Mr. Frank T. Swett, of Martinez, Cal., sent to the laboratory of
the Bureau of Entomology at Walnut Creek, Cal., a quantity of
pear leaves badly injured by this species. On August 31 Mr. Foster
visited the orchard and found the injury quite noticeable. He wrote
that "the foliage gave the appearance from a distance of having
been scalded." Mr. V. L. Wildermuth, of this bureau, sent speci-
mnens taken on alfalfa at Indio, Cal., on July 2, 1910. Mr. A.
McLachlan, of Davis, Cal., sent in specimens of this thrips on
October 13, 1910, with the report that they were injuring the buds
and tips of cotton.
Mr. W. B. Parker, of this bureau, under date of August 25, 1911,
sent this insect from Davis, Cal., with the statement that it was
causing serious damage to the foilage of the sugar beet. He also
collected it on sugar beets at Hamilton City, Cal., on September 18,
1911, where it was causing some injury. He wrote, however, that
owing to the lateness of the season when the beets were attacked
probably only slight damage resulted.

HABITS OF THE ADULT.

For a short time after emerging from the pupa this insect remains
quiet and appears to be waiting for its limbs to harden. During
this time the colors, which were light at emergence, gradually darken.
After hardening the thrips moves off and begins feeding.

METHOD OF MATING.

The males and females of this species seem to emerge from the
pupa at about the same time. During this investigation it was ob-
served that, under laboratory conditions at least, the sexes mated
generally in from two to three days after emergence and in some
cases in even less time. This operation has been observed both in
the field and in the laboratory and was identical under both condi-
tions. This is probably best described by the original field notes
made at the time of observation.
51097-Bull. 118-12----3





THE BEAN THRIPS.


The male,1 when inclined to copulate, picks out a female, and if :'"
she is moving over the leaf runs after her and jumps or alights on her
back. In some cases he then spreads the wings and moves them up
and down, at the same time moving the tip of the abdomen in the ;|
same manner. In other cases the male, after leaping onto the back j
of the female, remains motionless for some time in that position. It "
then exserts the copulatory organs from the tip of the abdomen and i
shifts around toward the side of the female, at the same time bend- (
ing the abdomen under to the ventral side of that of the female. The
copulating organs are then moved back and forth until they en- '
counter those of the female. In some cases observed, when the male
did not succeed in connection, it would withdraw to its former posi-
tion on the female and after remaining quiet for a short time would
move over and attempt the act on the opposite side. As soon as con-
nection is made the male remains motionless for a short time, during
which period the female, in many cases, crawls slowly around on :
the leaf. After a few minutes the male relinquishes his hold with
the copulating organs and moves squarely back onto the dorsum of
the female. Soon after the male crawls off and away from the female.
This entire operation was observed in three cases to occupy 3, 5, and i
10 minutes. Several cases were observed where two males attempted
copulation with the same female, but, after a vain attempt, one
generally left her.

METHOD AND TIME OF OVIPOSITION.

Exactly how much time elapses between copulation and oviposition
was not observed, but probably not more than a day, so that the .
female will begin oviposition within three days from the time she :!
emerges from the pupa. In one case adults emerged on July 19,
1911, and eggs were laid four days later.
Oviposition usually takes place during the night, but has been
observed at 2, 3, and 4.30 in the afternoon. A female engaged in
oviposition was observed to crawl over the leaf of the food plant
for a short distance and then to stop and scrape a hole in the leaf
with her mouth cone. This was accomplished by a slight forward
and backward motion like that of a chisel. In a short time the
female ceased this action and moving forward until she could. place
the tip of the abdomen where the tissue had been ruptured, arched
the abdomen in the middle, and brought the tip to the opening in ;
1Pietro Buffa (Atti Soc. Toscano Soc. Nat. Mem., vol. 23, p. 48, 1907) figures .olothripsa
fasciatus, female and male in copulation, in a position identical with that observed by
the writer in Heliothrips fasciatus on many different occasions. l
A. F. Shull (A Biological Survey of the Sand Dune Region of Saginaw Bay, Mich.,
pp. 190-192), describing copulation in the suborder Terebrantia, expresses doubt as to
the position of the male on the back of the female during copulation. As his observa- ,
tions on Euthrips tritici were made under unfavorable conditions his conclusions were :
probably erroneous. ..
3


18






HABITS OF THE ADULT. 19

the leaf surface. She then proceeded to work the ovipositor back
and forth in the rupture until she had made an incision of sufficient
depth. After this she became motionless for a varying length of
time, while the egg was being deposited, whereupon the ovipositor
was removed, and the female moved away.
A number of cases have been observed where the female, after
inserting the ovipositor, could not withdraw it, and, thus held, she
soon died.
NUMBER OF EGGS AND PERIOD OF OVIPOSITION.
Owing to the artificial means used in studying the habits of this
insect it was impossible to determine exactly how many eggs a
female is capable of laying. However, the writer confined 6 fe-
males in a vial for observation. They laid an average of 35.5 eggc
each, while the highest average for any day was 5.5 eggs each.
Another female, during the period from August 16 to August 23,
1911, laid 16 eggs, the greatest number laid in any one day being 5.
At Compton, Cal., during 1911, females kept in confinement were
observed to oviposit for 30 days in succession, while others were
observed to oviposit 51 and 83 days after they emerged from the
pupe. If this insect normally continues oviposition regularly over
a period of 83 days the total number of eggs laid must be very large.
Mr. V. L. Wildermuth, while in the Imperial Valley, made some
interesting notes on the number of eggs this species may deposit.
On August 2, 1910, he confined 2 females on leaves of alfalfa in
a vial, and on August 5 these leaves contained 50 eggs, or an average
of 25 eggs each in 3 days. His other observations are given in
Table I.
TABLE I.-Number of eggs deposited by the bean thrips (IHeliothrips fasc'iatus),
Imperial Valley, Cal., 1910.

Date and number o f eggs. Total
Ejper- Date female __________________period of Total
lment was put in vial. oviposi- umber
No. 1910. Eggs. 1910. Eggs. 1910. Eggs. Dead. tion. of eggs.

1910. Days.
1 Aug. 29 ....... Sept. 1 36 Sept. 2 6 Sept. 6 37 9 7 79
2 Aug. 31 ....... Sept. 4 42 -................ .............. 9 3 42
3 .....do. _.. Sept. 7 53 ......... ..... ............. ..... 9 6 53
4 .....do ........ Sept. 1 20 .......................... ....... 9 1 20
1911.
5 Sept. 28' ..... Sept. 30 12 Oct. 3 25 Oct. 11 24
Oct. 21 47 ... .... ii I...... 46 134
Nov. 1 27 Nov. 11 I
1 Record made at Tempe, Ariz.

In these experiments the longest period of oviposition was 46 days,
and the largest number of eggs laid by a single female, 134.
It will be observed from these figures that the females observed by
Mr. Wildermuth deposited more eggs and at a more rapid daily rate




I
20 THE BEAN THRIPS.

than those observed by the writer. This may have been due to the .
higher temperature of the Imperial Valley and vicinity, where his
observations were made. Mr. Wildermuth noted adults in copula-
tion the day that they emerged, and oviposition on the following "
date. He also observed this species to oviposit during the entire day,
whereas the writer never observed it to oviposit except in the after-
noon or night. '
PROPORTION OF THE SEXES.

The bean thrips was under the observation of the writer for a
period of more than two years, during which time it had been ob-
served in the field at all times of the year. In all observations made
during the investigation of this insect the males and females were
collected together and copulation was observed from early in Febru-
ary until reproduction ceased late in the fall. Apparently the
females outnumber the males, but this may be due to the fact that
the females are not quite so active as the males, and are not dis-
turbed on the plants when examined. On June 9, 1911, out of 17
specimens reared in the laboratory 9 were females and 8 males. July
17, 1911. the Writer examined another series of live adults that were
reared in the laboratory. Out of 106, 80 were females and 26 males.
A third series of reared adults was examined October 16, 1911, and
out of 44 adults 32 were females and 12 males. Apparently the per-
centage of females is too high and does not indicate the exact rela-
tion between the sexes.

KINDS OF REPRODUCTION.

In all observations made on this topic reproduction has been
bisexual, and in view of the fact that males were observed at all
times and copulation also occurred at all times in the year when
this insect was active, this would seem to be the usual method. How-
ever, although the few experiments made to determine whether
parthenogenesis occurred gave negative results, in view of the pre-
ponderance of females during certain parts of the season it is quite
probable that asexual reproduction may occur. It would seem that
this method would occur under certain conditions, especially in
view of the fact that the greenhouse thrips (Hfeliothrips humorroTi-
dalis)' reproduces, so far as we know, asexually only, the male hav-
ing never been discovered. ,
*!i;
FEEDING HABITS. I

Both the adult and larva of this thrips injure the host by feeding
on the foliage. As in the case of the greenhouse thrips, the lower :
1 "The Greenhouse Thrips," Bul. 64, Bur. Ent., U. S. Dept. Agr.





HABITS OF THE ADULT.


and earlier leaves are first attacked in the spring by the adults.
These feed on the underside of the leaves, scraping out the leaf
content in small spots that become white and conspicuous. Often
the adults move along and leave a chain of white spots to mark their
progress. The adults also feed to some extent on the surface.
As they feed the females deposit their eggs in the leaf tissues, and
as soon as incubation is completed the larvae hatch and join the
adults on the leaves. Under these conditions the leaves become more
or less dried and lifeless, and the adults move to the higher and more
tender leaves of the plant. In this way the entire plant may become
infested. On February 5, 1911, the writer found the adults of this
insect extremely abundant in the pea field of some Chinese truckers
at Hollywood, Cal. Here nearly every plant had 7 or 8 adults feed-
ing on the underside of the foliage, and in many cases 5 and 6 were
present on each leaf. On August 18 of the same year in the same
locality plants of spiny wild lettuce (Lactuca scariola) were observed
that had 50 adults feeding on a single leaf.
The adults seem to feed on a large variety of plants and have been
found feeding on all of the plants given under "List of food plants."
It may be well to state at this point that the presence of adults on a
plant has not been considered sufficient evidence to class that plant
as a food plant, but whenever larvae of this insect were taken on a
plant, this was considered sufficient to rank the plant as a host.
In the spring when the adults leave hibernation they collect on
the wild food plants present and feed on them until their injury,
due to an increase in numbers and feeding, weakens the plants and
shortens the food supply; then they fly to fresh plants of the same
hosts or to cultivated crops and fruit trees nearby. Of all the food
plants observed, the spiny wild lettuce (Lactuca seariola) seems to
be the most favored. This plant has been found to be infested more
heavily than any of the other food plants concerned, not excepting
those of economic importance.
FLIGHT.
The present writer in his investigations of the greenhouse thrips
never observed that insect to take flight naturally, or even when dis-
turbed. The adults of Helioth-rips fasciatus, on the contrary, take
flight very readily, and if jarred or disturbed will usually fly or jump.
This species in taking flight raises the tip of the abdomen quickly,
and separates the wings. It then rises straight up into the air and
flies rapidly away in short undulating curves. Indeed, to the un-
trained eye it appears, in flight, exactly like a small speck of soot
being blown around by a slight breeze. This power of flight aids
greatly in the dispersion of this insect during the spring and summer.
Loc. cit.


21





22 THE BEAN THRIPS. ~

LEAPING, f
This species possesses the power to leap actively and, considering .
its size, to a considerable distance. It is no uncommon- occurrence for '
the specimens which are being examined*upon a plant to leap off and.
be lost. Like the greenhouse thrips, it will crawl over the leaves
rapidly when disturbed. At other times it will remain motionless I
for a considerable period, lying closely to the surface of the leaf along 'I
one of the veins.
NORMAL LENGTH OF LIFE.

The length of life of this insect as an adult has been determined ,
under the artificial conditions of confinement in vials containing
fresh leaves of the food plant. As often as these lost their freshness
other leaves were put in and the adults were changed with a camel's-
hair brush..
Even under these conditions the length of life observed for some
individuals was surprisingly long, when we consider the minute size
of the insect. During these experiments it was observed that these
insects were very sensitive to humidity or a lack of it and all were
soon killed whenever the vials used in confining them became too dry.
Table II shows the results of these experiments in which some thrips
lived for 84 days.
,3
TABLE II.-Length of life of adult bean thrips alt Compton, Cal. 1911.

Specimens died. Mxm
Number Last Maximum _I
Dote adults emerged from pupa. emerged. adult length of
Date. Number. died. life.

Days.
April 16 ........................................... 3 (M ay ay 22 37
May 8 { 24
A pril23.......................................... 11 M ay 18 1 July 143 8
May 26 1
June 5 1
/ue17 5 }.u. 47
June 5............................................. 9 June 21 3 Aug. 14 71
July 22 2 1
July 25 2 1
July 19.. 4 J~uly 26 2[A g 21I :'
July19............................. ............... 14 Aug. 8 2 Aug. 21 34 :
Aug. 12 2 I
1Aug. 17 1 .1
I Dead. 2 Lost. 3 Male and female,'

LENGTH OF LIFE IN WINTER. *

A number of adults were collected from host plants on November
18, 1910, and were placed in vials and furnished with fresh leaves at i
intervals, and some lived in confinement in this manner until Febru-
ary 1,1911, by which time all had died. On January 16,1911, a num- j


I






HABITS OF THE LARVA.


ber of adults were taken from the open on leaves of nasturtium and
were placed in vials. These died in April, giving a length of life
after being collected of 92 days. As adults have never been observed
to emerge from pupae later than December 27, these adults must have
been at least 21 days old when collected, so that they lived about 113
days. Probably hibernating individuals live as long as .5 months.
HABITS OF THE LARVA.
0
In observing the habits of the larva of this thrips, the writer was
constantly impressed with the great similarity that existed between
this species and the greenhouse thrips. This is so great that the
description of habits of the one would almost equally fit the other.
HATCHING.

Apparently the hatching process may occur at any time during
the day. Many have been observed hatching early in the morning
and one larva was observed emerging from the egg cavity at 4.25
p. m. Very slowly this larva pushed its way out of the egg cavity,,
during which time the appendages were all held closely appressed
to the body and were invisible. As soon as the body was nearly out
the insect began a slow forward and backward movement and at
4.40 p. m. all but the tip of the abdomen was free, while the larva pro-
jected straight out from the leaf surface. While held in this position
it began slowly to unfold the limbs and antennae and move them
around. The motion was very feeble at first, but. gradually the larva
seemed to gain strength and at 4.48 p. m. it bent over and, grasping
the leaf surface, began to pull with its limbs in order to free itself.
This was accomplished at 4.53 p. m., making the total period required
in emerging from the egg 28 minutes.
The larvae of this insect after hatching move away a short distance,
then appear to rest for a few minutes until they become stronger.
Within a short time, however, they move on and soon commence
feeding. When first hatched the larvae are very minute and almost
colorless, but as they begin to feed and drain the green coloring
matter from the leaf the alimentary tract becomes plainly visible
from the contained food. In a few days the color of the body
becomes more or less yellowish and blotched with crimson. In com-
mon with other species of Heliothrips, the larvae of the present
species keep the tip of the abdomen elevated and carry around on it
a small globule of reddish liquid excrement. Gradually this globule
increases in size until it is too large to be carried any longer and it
falls to the leaf surface. Here in time it dries and forms a black
spot or scale. The occurrence of these spots on the leaf of a plant
1Tbis larva emerges from the egg by the same method that is used by the conchuela
(Pentatoma ligata Say) as described by Morrill (Bul. 86, Bur. Ent., U. S. Dept. Agr., pp.
38-39).


23





THE BEAN THRIPS.


marked by feeding of some thrips furnishes goodfevidence that the 1
bean thrips has been feeding there at some time. The larvae feed in l|
much the same manner as the adult, the mouthparts being practically |
the same. They gradually scrape out the contents of the leaf, leav- ,
ing silvery spots, which as they- become abundant often unite and l
gradually destroy the vitality of the leaf. Most of the eggs seem to
be laid on the underside of the leaves, although the writer has ob- .
served eggs to hatch from the upper side also. As a consequence i
the larva? begin feeding largely on the underside of the leaves. After :
hatching they do not move far before commencing to feed, during
which time, under ordinary conditions, they move very little. When
plants are first infested the larvae seem to feed close to the leaf
veins, but as they become more abundant they scatter in groups over
the entire leaf surface. Like those of the greenhouse thrips the
larvae of this species seem to cluster in colonies and unless disturbed.
or in need of fresh food, remain thus. The colonies are in many cases
found in between two veins of the leaves. When disturbed the larvM
will violently twitch the end of the abdomen with its drop of liquid
and move away rapidly. Apparently this is used as a means of de-
fense, for the writer, in work with a parasite of this thrips, observed
at times that these larvae when touched from in front by the parasite
flung the abdomen around and moved rapidly away. When this oc-
curred the parasite generally retreated, but returned to the attack
and later usually succeeded in ovipositing in its host.
The larvae and adults of this thrips feed together in colonies, and
as the leaves become crowded or dry from excessive feeding the"
larva? move in search of fresh food. Gradually the whole under-
side of the leaf attacked becomes infested by the larvae and then
the surface as well. In fact, the writer has seen leaves so heavily
infested by the larvae of this thrips as to give them a decidedly
larvae move in search of fresh food food. Gradually the whole under
reddish color, due to the bodies of the insects. So far this larva
has not been observed feeding in the blossoms of any plant,
but in some cases it has been observed feeding on green tomatoes,
and when bean vines are badly infested the pods are also attacked.
Indeed, when excessively abundant, these insects will not only
cover both sides of the leaves, but the stem of the plant as well.
The larvae as a rule feed unprotected on the leaf, but at times may
be found feeding under the protection of red-spider webs.
Apparently these minute creatures are not affected by dust, as
the. writer has found them feeding in large numbers on leaves of
spiny lettuce in an alley in the city of Los Angeles when the leaves '
were so thickly covered with dust as completely to hide the surface. i.
It would seem that with the enormous clouds of dust that arise in
this section during the entire summer, completely coating the larvae, 3
they would speedily succumb.


24






HABITS OF THE LARVA.


As an illustration of how abundant this insect may become, the
following observations are given: On August 31, 1909, Mr. Foster,
of this bureau, found it severely infesting pear foliage at Martinez,
Cal., and noted as many as 200 larvae on one side of a leaf. On
July 28, 1910, the writer found some plants of spiny lettuce badly
Infested by the larvae of this thrips, and 10 leaves gave a total infes-
tation of 733. (See Table III.) This gave an average of 73.3 to each
leaf.
TABLE III.-Infestation of Lactuca scariola by larvw of the bean thrips.

I Number Number Total Number Number Total
No. of of larvme of larvae numberof No. of of larvae of larvae number
leaf. on under onuipper larvae leaf. on under on upper of larvae
side. side. on leaf. side. side. on leaf.

1 70 7 77 7 44 47 91
2 34 39 73 8 61 30 91
3 43 2 45 9 70 1 71
4 30 2 32 10 23 32 55
5 59 47 106 -
6 46 46 92 480 253 733

On July 18, 1911, at Hollywood, Cal., leaves of spiny lettuce were
found that had several hundred larvae to a leaf. September 22, 1910,
Mr. Wildermuth observed a field of cotton at El Centro, Cal., show-
ing considerable injury by this insect, and counted as many as 200
larvae to a single leaf.
MOLTING.

The larva molts once, giving two larval instars, then molts to the
prepupal stage. On July 28, 1910, a number of larvae that had just
hatched were separated and on August 2 these all molted. On August
7 they again molted and changed to prepupae. This gaVe the first
instar a length of five days and the second a length of five days. The
process of molting in the larva is continued unprotected in the midst
of the feeding colony. After molting the skin is left adhering to the
leaf beside the feeding larva.
It was observed with the larvae of this species and of those of the
greenhouse thrips that when they were exposed to a low temperature
the entire development was checked and growth remained stationary
during the exposure. In long-continued exposures the insects were
killed, but if within three weeks they were again removed to higher
temperatures the larvae resumed their growth and pupated in a
few days.
Under the artificial conditions of rearing in vials the mature
larvae seek concealment before pupation in curled-up leaves, in all
kinds of protected places, and if in vials closed with cotton plugs
they work their way in between the plug and side of the vial. In
the field, however, the larvae when full grown desert the plants and
hide in rubbish and cracks in the ground or beneath clods of earth.
51097-Bull. 118-12-----4


25




THE BEAN THRIPS.


The molting from larva to prepupa under laboratory conditions has
been observed many times. On April 10, 1911, a mature larva was
observed to begin the process at 4.05 in the afternoon. After remain-
ing motionless for some time it arched its body, and shortly after
the skin split down the head behind the antennae. The head grad-
ually forced its way out of the opening, then the body followed, the
old skin being slipped off behind. This molting was completed at
4.21 p. m.
HABITS OF THE PREPUPA AND PUPA.

The prepupae of this insect are found in company with the pupae
and full-grown larvae in small social colonies. These hold the
antennae out in front of the body and move about to some extent.
The pupae, however, carry the antennae folded back on the head and
thorax and remain motionless unless disturbed or exposed to the
light, in which cases they will slowly crawl away. When com-
pelled to pupate in closed vials the prepupae and pupae occur in
large numbers closely packed together along the edge of the vial
and the cotton plug or buried in the cotton itself. In nature it has
quite different habits. While the greenhouse thrips under natural
conditions pupates on the leaf of the food plant in among the feeding
larvae, with the bean thrips this seldom takes place, and during the
two years this species has been under observation by the writer only
three pupae have been found on the plants infested by hundreds of
thousands of larvae. In one case a pupa was found under the web of
the red spider near the midrib of a leaf of spiny lettuce; in another,
one was found under a web of red spider on a leaf of the wild tobacco
flower; and the third was found in a curled-up lettuce leaf.
December 17, 1910, a quantity of the dead leaves of wild helio-
trope were collected on the ground under infested plants. Prolonged
sifting revealed the presence of a single pupa. In 1911, the prepupwe
and pupae were found by Mr. John E. Graf and the writer to be
very abundant. in infested bean fields under clods or lumps of dry
earth and in cracks or holes in the lumps. Upon exposure to the
light these at once began to move away in search of darkness.
Mr. Wildermuth also found the pupae of this insect underground.
He wrote in his notes on September 23:
While searching by aid of a binocular for pupae. I found one pupa, one
prepupa, and two (mature) larvae just at the crown of the plant and beneath
the soil: oue pupla about one-fourth inch below the surface of the soil in an
oval cavity about three times as long as the pupa itself; one prepupa between a
dead leaf and the soil. Never have I found a pupa above the surface of the
ground, on the leaves of the plant, or between the .sheath leaves and the stem,
as frequently occurs in confinement.
The molting of the prepupa to the pupal stage is very similar to
that described for the change of the larva to the prepupa. It takes


26





FOOD PLANTS.


place in whatever location the prepupa may be, and the transparent
and delicate empty skin is found behind the pupa. It was observed
during the fall that pupae exposed to a low temperature did not com-
plete their development to the adult stage. These, when later placed
in the greenhouse, changed to adults unless exposed to the unfavorable
conditions too long, when all were killed.
During the pupal stage several external changes take place. At
first the ocelli are not evident, but as the pupa develops these become
prominent in a triangle between the folded antennae. Then the reticu-
lations of the body begin to appear, and within two days of the
emergence of the adult the pupa begins to darken and the legs,
antennae, and wings begin to show blackish bands. The adult
emerges in a manner similar to the molting of the larva. Emergence
has been noted at all hours of tlie day, and there seems to be no par-
ticular time for its occurrence.
FOOD PLANTS.
This insect seems to be nearly as omnivorous as the onion thrips,
as the following list of food plants upon which it has been reared or
observed during the past two years by the writer would indicate.
These have been divided into economic and wild food plants, and
under each will be given notes on injury and appearance of injured
plants.
BEANS.
The injurious occurrence of this insect on the foliage of beans gives
to it its common name. It has been observed by the writer to feed on
bean foliage in the adult and larval stages from early in February,
in sheltered places, until the plants are killed by frost in the fall.
In the spring the wild plants are first up, and the attack is largely
concentrated on them, so that when the beans come up they are not
immediately attacked. However, in a few weeks the insect spreads
to the beans, thereafter increasing in numbers until in the late sum-
mer and fall much injury is done. When snap beans are infested
the adults first attack the leaves, and while feeding lay countless eggs
in the tissue. The larvae on hatching begin to feed, and gradually
the green coloring matter is entirely removed from the underside of
the leaf. This becomes white and covered with the black spots of
excrement. The infestation then spreads to the surface and to other
parts of the plant. As the feeding goes on the leaves lose all color,
become white, or dry up and turn brown and drop off. As the infes-
tation increases, the stems and pods themselves are also attacked and-
ruined. A badly infested field appears as if scorched by fire. The
lima bean and pink bean suffer in the same way. The blackeye cow-
peas this past season were almost inummune from the attack of this
insect, even in fields in which the pink beans and spiny lettuce were
very badly infested.


27




'H
28 THE BEAN THRIPS. :

OTHER VEGETABLES.:i

During the spring and early summer this insect is not noticeable.-
on either the sugar or table beets. Late in the summer, however, as .... ::.:
the wild plants die down, these plants often become badly infested, | "
but as the beets have nearly completed their growth little real in i
jury results. The outside leaves seem to be first infested, showing-:-::...,
series of minute white spots more or less in chains, where the chloro-
phyll has been removed, but in badly infested leaves the underside
becomes white and dried and covered with small black spots, causing "'
A / ^3r """:!!!?
the leaves to wilt. Mr. Parker wrote from Hamilton City, CaL,
under date of September 18, 1911, that the injury was apparent in "
almost every field.
Cabbages and other crucifers are commonly infested by this thrips
and at times may be seriously injured. On March 27, 1911, cabbages
in the laboratory yard were slightly infested. Where they had fed
long the underside of the leaf was f till of the silvery-white feeding.
marks of this insect and the tiny black specks of excrement. Cauli-
flower suffers to the same extent as the less valuable cabbage.
This insect has also been found feeding quite extensively on let.
tuce, potato, and tomato. At Hollywood, Cal., in February, 1911,
it was very abundant on the foliage of pea vines, but the. infestation
did not appear to increase, probably because the vines were quite old.

PEAR.
P.&M

Mr. S. W. Foster found pear foliage badly injured on August 31,
1909, at Martinez, Cal. Hlie wrote:
The foliage gave the appearance from a distance of having been scalded.
Close examination showed that the leaves were often injured in large areas on1
either or both surfaces. The larvae, feeding only on these outer surfaces, soon
cause the blackened areas. ,,
As the tree has made most of its growth for the season and the fruit crop .]
has been harvested, it is hardly probable that this species will prove of serious
consequence to the growers unless it should get so numerous as to appear in ;
numbers early in the season.
ALFALFA.

The following field observations on the work of the bean thrips
on alfalfa and cotton were made by Mr. Wildermuth in the Imperial
Valley, Cal.:
August 2. 1910. This thrips does nearly all if not all of its feeding an the
upper surface ot the leaf. The excrement is arranged in definite rows, often
semicircular in form, around these eaten spots and makes a very characteristic .'
mark [see fig. 9]. The eaten spots later turn yellow and then the alfalfa
presents a sickly appearance. August 4 I visited several alfalfa fields and all :
were very much injured by this thrips. Scarcely a leaf could be found that C ..






FOOD PLANTS.


29


was green and fresh as it should be. The fields examined have a whitish-
yellow cast to the usual green appearance. August 30 several fields were
visited and every leaf in the fields examined was attacked by the thrips. The
alfalfa has a whitish and bleached appearance, due to the effects of the thrips'
feeding. I never saw anything to equal this in appearance or in thoroughness


1.:


FIG. 9.-Alfalfa showing injury by the bean thrips.


(Original.)


of attack. September 30 the fields were still being badly damaged. After a
field is newly irrigated just after cutting for a week or 10 days the damage is
not noticeable, but after three weeks nearly all leaves show the effects and the
alfalfa presents a very sickly appearance. A lack of sufficient water causes
the damage to be more noticeable, as under such a condition the growth of the
alfalfa is not so rapid and the thrips' damage is more conspicuous.




*-i
30 THE BEAN THRIPS. *

On September 18, 1911, he wrote:.,
This thrips is very abundant in alfalfa fields at this time of year, the larva
being present on the older alfalfa and the adults present on the younger shoots
and leaves. Many leaves, after being badly scarred by the thrips, wilt and fall n i
off, so that the damage is soon very great. It seems rather strange that this :
thrips should become so vAry abundant in the fall of the year and Euthripa
tritici, the other important alfalfa thrips, should decrease in numbers and
that in the spring of the year just the opposite should be the case. '

COTTON. '
September 22, 1910, Mr. Wildermuth wrote:
This thrips was found damaging cotton about 11 miles southeast of El
Centro, Cal. The cotton was only damaged in one corner of the field, and it
happens that fresh alfalfa is being stacked close to this corner.
September 28 a field of cotton east of Imperial had a strip through the center
of the field damaged by this thrips. September 30 numerous fields on the east
side of the valley were being damaged by this pest. The leaves were dead and
rusty looking and the plants in bad condition. The damage was not as great as
if the work had begun earlier in the season, but was at that time very great.
October 11 several cotton fields at Holtville, on the east side of the valley,
were examined. A great many fields showed considerable injury. The leaves
were eaten and turned a sickly yellowish or brown, many often being curled.
A field on the Young ranch was as badly damaged as any seen, and this field
lay alongside an alfalfa field. Three other fields on the same ranch showed
very little damage. The former field was of a late planting. This thrips has
caused much more damage to cotton than was anticipated, and if it should
begin its work early in the season it might prove extremely destructive. Be-
cause of this, as well as other still better reasons, cotton should be planted as
early as possible in the spring.
In November, 1911, Mr. Wildermuth wrote:
Mr. Packard and cotton growers throughout the valley report but little injury
to cotton by this thrips this year. I found only two specimens of larvae myself,
qnd a few adults. It would seem as if the damage to cotton comes when cotton
follows alfalfa. This year, there being but little alfalfa land put to cotton .
and more cotton following cotton, the damage was not so noticeable.

WILD PLANTS.

Of all food plants of this insect the wild spiny lettuce (Lactuca
scariola) seems to be preferred, at least in the vicinity of Los Angeles.
From early spring, when this plant comes up, until it dies down in.
the fall, it is usually badly infested by thrips. Many cases have been
observed where other food plants, such as beans, etc., in the same field '
were only slightly infested, while the spiny lettuce near by was so i
badly attacked that many plants were dead. Furthermore, this weed .
is one of the commonest in the country, occurring abundantly in un-
cultivated or even in badly cultivated fields. In addition it grows
up in dense clumps in all fence rows and roadsides, and the rights
of way of the different railroads are densely packed by this plant. i





SEASONAL HISTORY AT COMPTON, CAL.


When this weed first comes up in the early spring there is scarcely
any vegetation, so that it offers an agreeable host to the bean thrips,
especially as the foliage is very tender and juicy at that time. The
thrips attack the first young leaves, and the larvae, upon hatching
from eggs deposited at that time, join the feeding adults. As soon
as these become abundant, the leaves lose all or nearly all of the green
leaf-content and turn white, after which they dry up and hang dead
from the stalk. The infestation continues to spread to the younger
leaves until the entire plant is killed.
The sow thistle (Sonchus oleraceius) has the same general distri-
bution and is also a favorite food plant.
Wild heliotrope (Heliotropitium. cnrcessavicum) is another favorite
food plant late in the year. This plant does not start in the spring
until quite late, and when it does appear above the ground generally
escapes destruction by cultivation. Thus it occurs commonly in the
beet and bean fields and in orchards, and in the fall is one of the
chief food plants.
The bean thrips has also been found feeding and reproducing in
numbers on Euryptera lucida and on one of the cucurbitacewe, prob-
ably an Echinocystis, in a canyon north of Los Angeles. In the same
locality it was later taken feeding and reproducing on Gnaphalium
ealifornicum, Mirabilis californica. Eunanus brevipes, (Chenopodiumr
murale, helianthus annuum, Atriplex sp., wild turnip, Erigeron cana-
densis, and wild pea (Lotus americanus). It was also taken in the
valleys feeding and reproducing on the Chinese cigarette flower (.Vic-
otiana glauca), Bidens pilosa, Verbascum virgatum., Polygonurr avi-
culare, and Crepsis (?) sp. The adults were also taken in the fall
feeding on the foliage of a porch vine, Tacsonia mellissimus, and on
the cultivated nasturtium (Tropceolum major). Mr. A. C. Morgan
found it on the underside of the leaves of the tulip poplar at Clarks-
ville, -Tenn.
This thrips has also been recorded as feeding on Lotus glaber,
apple, peach, orange, wild vetch, burr clover, and radish.
After perusal of the above list of food plants it is easy to see how
this insect can obtain a foothold in a cultivated crop in the late
summer, especially as many of the wild plants die from maturity or
lack of moisture, thus forcing the insect to migrate.
SEASONAL HISTORY AT COMPTON, CAL.
The life cycle of the bean thrips was observed at Compton for vary-
ing parts of the year, and because of the cooler and more even tem-
perature prevailing there is quite extended and more nearly equal
for the entire period of reproductive activity.
THE EGG.
The length of time required for the egg to hatch in the months of
March, April, and May was not exactly determined. However, fresh


31




ul

32 THE BEAN THRIPS.

leaves of wild lettuce were collected on April 7 and they had a
number of eggs in them very recently laid. The last of these hatched
on April 24. making the length of incubation about 17 days, or possi- I
bly as many as 21 days. The average mean temperature for these
21 days was 59.1 F.
In July several adults of this thrips were confined over night on
leaves of growing plants that were uninfested, and were removed
on the following morning. In this way a number of eggs were ob-
tained that hatched under absolutely normal conditions, -s the plants
were kept in an open-air insectary.
Table IV has been prepared to show the records of incubation for
these eggs.

TABLE IV.-Length of egg stage of the bean thrips in July at Compton, Cal., 1911.

Dates eggs hatched and number each day.
Date of First egg Last egg Shortest Longest Total
ovipo- iistg hLhsthoeh incubar incuba- eggs
sition. Jul July July July July! July July July hatched. hatched. tion. tion. hatched.
23. 24.1 25 27. 28. 29. 30.

SDays. Days.
July 10 5 54 16 3 2 6 .......... July 23 July 28 13 181 86
July 11 ..... 26 18 9 7 ..... ..... .... July 24 July 27 13 17' 60
July 14 .....- ..... ..... ........ 8 15 ..... July 28 July 29 13 14 23
l i 169


In this experiment 169 eggs hatched and the minimum length of
incubation was 13 days and the maximum 18 days, but nearly 50
per cent hatched in just 14 days. During this total period the aver-
age mean temperature was 69.6 F.
Again, on August 20 adults were confined over night on a living
plant of wild lettuce, and 4 larvae hatched on September 4, and 7 on
September 5, making the periods of incubation 15 and 16 days.
During this time the average mean temperature was 66.3 F.
During the months of October and November the incubation is
probably lengthened a few days and will take about 21 days, as the
average mean temperature for these months was, respectively, 58.67
and( 55.3 F.
THE LARVA.

The length of time occupied by this insect in the larval stage dur-
ing the months of March, April, and May was observed during the
year 1911 by confining larvae that had just emerged in vials con-
stantly supplied with fresh food. Table V gives the results of these
observations. While in the first part, of this period the length re-
quired was from 17 to 19 days, later it was shortened to 9 and 11
days. The average mean temperature for the first period, March
19 to April 7, was 61.5 F. and for May 14 to May 27 it was 61.1 F.

-i







SEASONAL HISTORY AT COMPTON, CAL. 33

TABLE V.-Length of larval stage of the bean thrip.. Compton, Ca!., March and
May, 1911.


Date larve hatched.


Mar. 19 ..............................
M ay 14 ...............................
M ay 16 ....................... ........
M ay 18...............................


Number
of larve
hatched.


Larvme pupating.

Date. 'Number..


Apr. 5 1 I
Apr. 6 2 2
Apr. 7 1
May 24 1I
iMav 26 4
May 27 1
May 27 4


Length stage. Average
_____________ mean
tempera-
iinimrun. Maximum. ture.

Days. Days. i F.
17 19 61.5


10
10
9


11 62.1


62.1


SRest killed by heat.

During June and the first part of July this method of rearing
larvT to secure the length of instars was repeated, with the results
shown in Table VI.

TABLE VI.-Lcngth of larral .xtagc of the bcan thrip., in Juine and the first part
of July, 1911. ('ompton, Cal.


Eggs hatched. Larvae pupated. Duration of stage. Average
Exp. ________________________ Total .... mean
No. pupated. tempera-
Date. Number.' Date. Number. Minimum. Maximum. ture.
I I

J Days. Days. 0F.
1 June 15.............i 5 July 1 1 2 13 16 63.9
IJuly 10 3 |
June29 ............. 50 JulyV 11 4 11 11 13
jJulv 12 4 66.7
i1July 11 7 11 1I 12
June29............. 50 '{July 12 4
July 1 ......... ..... 50 July 13 3 3 12 ......................


Here the minimum for the larval stage was 11 days and the maxi-
mum 14 days.
In July larvae were reared from eggs laid in normal growing
plants, situated in an outdoor insectary under normal conditions.
These experiments are all given in Table VII.

TABLE VII.-Length of larval stage of the bean fhripoj in .Inly. 1911, at Compton,
Catl.


Eggs hatched.

Date. I Number.


July
July
July
July
July
july
July
July


Date and number of larvm
pupating.


Total
larvae
pupat-
ing.


Length of larval stage.

Minimum. Maximum.


Days.
STuly 31, 85 larvae feeding; Aug. |
2, all but 10 left plant to pu- Sj 10
pate; Aug. 5,10 prepupoe.
Aug. 2, all larvae left plant to 1
pupate incracks. These lar- [
vse were feeding from 7 to 9; -----.-----
days and then left the plant.J
Aug. 9, number of larve pu- I ....... i1
pated. I


Days.
12


Exp.
No.


Average
mean
tempera-
ture.

0 F.
68.8


68.8

65.4


L------- ----- '---------------


}


............
............
I






34 THE BEAN THRIPS. J

In these experiments the larvae were observed to feed for a period
of 9 to 10 days and then to leave the plant to pupate, and 10 to 12
days were required between hatching from the egg and changing to l
prepupae. x
During the year 1910 a number of larvae that hatched on July 28 ii
were observed to change to prepupae on August 7, the total length ;
of the larval stage being 10 days, with an average mean temperature ]
of 72.1o F.
The length of this stage later in the summer and in early fall
for this locality unfortunately was not observed, but was probably
ip
somewhat shorter for August and September and considerably
longer in October and November. I

THE PREPUPA AND PUPA.

As the prepupa and pupa are two distinct stages, although closely
related, the length of each was separately determined. These two
stages during the spring of 1911 required from 3 to 6 days for the
,i
prepupa and from 9 to 14 days for the pupa, or a total of from 14
to 19 days. The results are shown in Table VIII, with the average
mean temperature for each experiment.

TABLE VIII.-Length of prepupal and pupal stages of the bean thrips at Comp-
ton, Cal., during March to May, 1911.
Lrwcagdtpr- Prepupse Adults"
Larw changed topre- e Adults Length of stage. ._
pupa. to pupae, emerged. Average
Exp mean
No. n tempera-
Num. ture.'
Num- D Num- Num- Pre- tin.
Date. Num- Date. r. ua- her. pupal. Pupal. Total.
D t.ber. bet. e. pupal.

SDays. Days. Days. F..
1 Mar.31............... 5 Apr. 3 5 Apr. 17 5 3 14 17 59.2
2 Apr. 10............... 1 Apr. 15 1 Apr. 24 1 5 9 14 59.5
Ap.Apr.24r._ 25 _ _
3 Apr.19............... 1 Apr.25 1 May 4 1 6 9 15 57.9 '
4 Apr. 24 ............... 2 Apr. 29 1 May 10 1 1 5 11 16 56.9
T otal........ 9 . .... . I 8 ........ ........ ........ .......... ,
Total..........t 9I.. ._____

In the month of July these stages required from 1 to 4 days for the
prepupa, and from 4 to 7 days for the pupa, or a total of from 5 to 11 :
days. The number that required less than 7 days, however, was very
small. During this month the average mean temperature was 69 F.
Table IX shows the results of these experiments and the average
temperature for each.
*:i !!l
... 4i-
9
'I. I
'4
SI.:
.,::.1






SSEASONAL HISTORY AT COMPTON, CAL. 35

TABLE IX.--Length of prepupal and pupal stages of.the bean thrips at Comp-
: ton, Cal., during July, 1911.

Chagedto reppa. Changed to Adults
Chaged to Adults Length of stage. r
pupa. emerged. Average
Exp. _________________ _________ _________ ______ mean
No. tempera-
Date. Num Date. Num- Date. Num- Pr e- pal. Total. ture.
Date. ber. ber. ber. pupal.

July I 2 Days. Days. Days. F.
1 Julyl............... 7 July 5 7 July 12 5 4 6-7 10-11 71.7
July 10............... 3 July 13 3 July 13 3 3 5 S
JJuly 14 6 7july 1.0 7 3 4 70
2 JulyJu.............. 7 y 15 1 70.1
J uly1 15 2J 912 4
Julyl13............... 3 {{ July 15 2 ...... 1- 45 57
f July 15............... 1 July 17 1 July 24 1 2 7 9 71.6
"(July lfi6............... 1 July 18 1 July 24 1 2 6 8
4 (July 19............... 2 July 23 2 July 29 2 3 6 9 63.5
J uly20............... 2 July 24 2 July 29 2 3 5 8

During the month of August, 1910, at Los Angeles, Cal., larvae
changed to prepupae August 2 and the adults emerged on August 9,
requiring 7 days for the prepupal and pupal stages. For this period
the average mean temperature at Compton, 10 miles out, was 72.4 F.
Another lot changed to prepupte on August 7 and the adults emerged
on August 15, giving a total of 8 days for the prepupal and pupal
stages. The average mean temperature at Compton for the period
was 71.4 F.
For the latter part of August and for September the length of these
stages is nearly that required in July. However, in October this
time is lengthened to some extent. Larvae that changed to prepupa
on November 3, 1910, required until November 16 before the adults
emerged, or a total of 13 days. The average mean temperature for
the period was 59.9 F.
Records made of the length of the prepupal and pupal stages for.
November and December, 1910, as given in Table X, show that at
that time of year the period required was greatly prolonged, the
prepupal stage requiring from 7 to 9 days and the pupal stage from
20 to 24 days, making a total period of from 27 to 33 days. During
this period the mean average temperature was 53.58 F.
TABLE X.-Length of prepupal anid pupal stagesc of ficthe bean thrips for November,
1910, at Comptoln, Cal.

' Changed to prepupa. Changed to pupa. Adults emerged. Length of stage.
Exp.
No. Pre-
,, Date. Number. Date. Number. Date. Number. pupa Pupal. Total.
pupal~. a. Ttl
,. Days. Days. Days.
S1 Nov. 14............ 1 Nov. 21 1 Dec. 12 1 7 21 28
|2 Nov. 16............ . 2 Nov. 23 2 Dec. 13 1 7 20-22 27-29
'! 2 N v. 6. No. 2 2 Dec. 15 1
f.. Nov. 251 4 Dec. 15 1 8 9 22-24 30-33
S3 Nov. 17 ............ 7 Nov.26 2 De 17 3 22-24
or.. 2... or 27. 1
Total ........... 10 9 7............ .




A
36 THE BEAN THRIPS.

TOTAL LIFE CYCLE. ]
For localities with climatic conditions similar to those of Compton, I
the life cycle of this thrips will occupy during the early spring about I
51 to 56 days, taking 20 days for the egg incubation, 17 to 19 days :
for the larval development, and 14 to 17 days for the prepupal and
pupal stages. :
During the months of June to October the life cycle of this thrips
will occupy from 28 to 43 days, taking 13 to 18 days for the egg ::
stage, 10 to 14 days for the larval stage, and 5 to 11 days for the
prepupal and pupal stages.
During the rest of the breeding activity the life cycle must be even
longer than in the spring, as in November, 1910, the prepupal and
pupal stages alone occupied from 28 to 33 days, so that for the de-
velopment of this insect during October, November, and the first of
December at least 68 to 73 days must be required.
EMERGENCE FROM HIBERNATION.
In 1912 the adults began to emerge from hibernation at Holly-
wood, Cal., in January, and began oviposition at once. When this
locality was visited on February 7, the adults were found to be feed-
ing on the foliage of peas and beans in some numbers. They were
also seen in copulation in many cases. A careful examination dis-
closed 4 young larvte feeding on bean foliage, so that the adult must
have laid the eggs at least by January 10. This field was situated
on the foothills of what is termed a frostless belt, and it may be that
tis insect in mild winters might breed there during the entire
period.
On February 17 adults were found feeding on pea foliage in Mis-
sion Valley, San Diego County, but no young were seen. February
23 the species was found as an adult feeding on pea vines in the truck
farms around Los Angeles, and on March 13 adults were found feed-
ing in small numbers at Compton, Cal. From then on the adults were
common feeding on different plants, but not until April 17 were the
larva found feeding in the open at Compton, although they were
being reared in the open insectary at that place from material col-
lected at :ollywood.
It would probably be better to say that this insect begins active
reproduction at a varying time, those in the most protected places
starting as early as January 10, and the others over the next 60 days.
However, during the early spring the multiplication and spread
seem to be very slow.
ENTRANCE INTO HIBERNATION.
As the month of October appears, the adults become sluggish, do
less feeding and lay fewer eggs, and apparently many enter hiberna-
:!:
*1!!
,..





SEASONAL HISTORY IN THE IMPERIAL VALLEY.


tion. The larvae become much less numerous and require an extended
period to complete their growth. In 1910 the last larvae in numbers
were observed in the field on November 20, while one was observed on
December 1, and three on December 13, and during the first part of
December these had all changed to pupae or died. The last adult
appeared on December 27. In 1911 the larvae were not very abundant
after the first week in October, and the last ones were observed in
Los Angeles County on November 21.

NUMBER OF GENERATIONS.

In the section of the State in which this insect was under observa-
tion, the first spring generation may commence as early as January
10 and probably egg-laying by overwintering adults continues for a
considerable time. As the period of oviposition is quite extended the
different broods tend to overlap; still in midsummer there are certain
periods when the majority of thrips present may be adults or larvae.
Up to April 1 there is probably one small full generation occupying
about 56 days. During April and May a second generation will
develop; then during the four months of June, July, August, and
September there is one full generation for each month. For the rest
of the period of the breeding activity we have probably a partial
brood that extends over 68 to 73 days.
Thus during the year this insect has a small generation in both the
early spring and late fall and five full generations during the rest of
the time, or seven generations a year.
SEASONAL HISTORY IN THE IMPERIAL VALLEY.

The observations on the life cycle of this insect for Imperial Valley
were conducted by Mr. V. L. Wildermuth at El Centro, Cal., in 1910.

EGG PERIOD.

Mr. Wildermuth confined adults in vials with fresh sprigs of
alfalfa and kept the foliage fresh by wrapping the stems in moist
cotton until the larvae hatched from the eggs. While many eggs were
secured by this method, large numbers died before hatching, as the
foliage became too dry. but, as shown in Table XI, the egg stage
varied from four days in a single case to five days in a lot of 20 eggs
laid the last day of August. The length of the egg stage at that
locality was only one-third as great as that observed by the writer in
Los Angeles County, but this is due in a large measure to the high
temperature of the Imperial Valley.


37





I Records missing.


2 Many.


3At Brawley.


LARVAL PERIOD.

The active feeding larva molts once before its final molt to the
prepupal stage. This occurs in from one and one-half to two days
after it hatches from the egg. The larva becomes full grown and
changes to the prepupa in from four and one-half to five days. As
might be expected from the great difference in the incubation period
of the egg, the larval period in the Imperial Valley, as observed by
Mr. Wildermuth, is much shorter than at Compton. These data
are given in Table XII.

TABLE XII.-Length of laral! stage of the bean thrips at El Centro, Cal.,
during 1910.


I Eggs hatched.
Exp.
No. i
Date.


1 Aug. 15............---
2 Aug. 158 .................
2 A ug. IS. ..... .. ... .. ..
3 Aug. 26 .................
4 Sept. 1 ..................
5 Sept. 22.................
Total .............


Number.


1
3
1
1
1
7


Molted.


Date.


Aug. 16
Aug. 19
Aug. 28
Sept. 3
Sept. 24


Number.


Changed to
prepupa.

Date. Number.


1 Aug. 19
1 Aug. 22
1 Aug. 31
1 Sept. 5
1 Sept. 27
5 I .........


Length.



Days.


Average
mean
temper-
ature.


OF.


1 4 85.8
1 4j (1)
1 5j 91.9
1 4 89.7
1 5 81.8
5 -----.......-- .........


Records missing.

PREPUPAL AND PUPAL PERIODS.

Unfortunately Mr. Wildermuth's records give a very small amount
of data on the length of the prepupal and pupal periods, but in the
six examples observed (see Table XIII) the stages varied from 2
to 3 days. While the writer was studying the greenhouse thrips
the prepupal stage was often observed to last only a few hours, and
this same condition probably occurs with the present species in the
high temperature of the Imperial Valley.





3 8 THE BEAN THRIPS.

TABLE XI.--Length of incubation of the eggs of the bean thrips, El Centro,
Cal., 1910.


Eggs hatched. Average
Date of oviposition. Number --Length mean
laid. of stage. tempera
Date. Number. ture.

Days. OF.
July 27. ................................... 2 Aug. 1 2 4j (1)
Aug. 11... . ...... ......... ......... .... .... (2) Aug. 15 1 4 387.1
Aug. 31......... ................. ............. (2) Sept. 6 20 5 '88.7


I
I
4
I
I



9






HIBERNATION.


TABLE XIII.-Lengt/ of prepupal and pupal stages, El Centro, Cal., 1910.

Date Length Average
EXP. Date changed to prepupa. adult of tmeanr
No. emerged, period. temper-
attire.

Days. F.
1 Aug. 19....................................... .................... Aug. 21 2 -3 (1)
2 A ug. 22 ........................................................... A ug. 24 2 (1)
3 Sept. 6.................. ....... ............ ....................... Sept. 8 2-2A 284.9
4 Sept. 4............................................................ Sept. 8 3 285.1
5 Sept. 7............................................. .............. Sept. 9 2 287.0
6 Sept. 27............................ ............................... Sept. 29 21 (')
SRecords missing. 2 Temperature at Brawley, LT. S. Weather Bureau.

In the Imperial Valley the egg stage is from 44 to 5 days, the
larval stage from 4 to 5 days, and the prepupal and pupal stages
from 2 to 3 days, making the total life cycle only 10 to 124 days
during the extreme summer temperature.
The eggs were deposited within 2 days from the time the adult
females emerged, so that a new generation might occur every 14
days in midsummer. If the insect emerges from hibernation in the
Imperial Valley at the same time as in Compton, there will un-
doubtedly be 1 generation in the early spring occupying 30 to 40
days, and then 2 generations a month for 5 or 6 months and 1
longer generation in the fall, or 12 to 14 generations a year. Indeed,
with such rapid multiplication it is not strange that crops in the
late fall become seriously infested.

SEASONAL HISTORY AT TEMPE, ARIZ.

Mr. Wildermuth during October and November, 1911, made some
observations on the life cycle of this thrips at Tempe. These gave
a life cycle of very nearly the same duration as in the Imperial Valley
in the warm weather, but in November the cycle was lengthened
considerably. He found that specimens collected as larvae on October
30 did not emerge as adults until December 1. This shows the same
effect of cooler weather on this insect that the writer observed at
Compton, Cal.
Taking the results of Mr. Wildermuth's and the writer's observa-
tions on the bean thrips, there is a minimum life cycle of 10 days
where the average mean temperature is about 88.75 F., and a maxi-
mum of about 73 days with an average mean temperature of about
53.58 F.
HIBERNATION.

This insect hibernates as an adult only, through most of its dis-
tribution at least. It may be that in the more southern portions of
its range it breeds continuously throughout the year, but our obser-
vations in these localities mentioned have failed to show it.


39





40 THE BEAN THRIPS.

In the section around Compton, Cal., the adults were found to i
hibernate in small numbers on the underside of leaves of nasturtium,
sugar beets, wild heliotrope, and other plants. They were also found
hiberating in some numbers in dead leaves and rubbish. When dis-
turbed they were sluggish and made little effort to escape.
Mr. P. R. Jones (in litt.) says that around Lindsay, Cal., the adults
hibernate in numbers in the navel end of the Washington navel
orange. He also stated that in midwinter he had taken this thrips ,
along creek beds hibernating on the underside of leaves of wild rasp-
berry and blackberry which were still on the plants.

NOTES ON OCCURRENCE. 4

Apparently the different methods of cultivation bear strongly on the
abundance of these insects and consequent injury they may cause to a
crop. In Los Angeles County, where clean cultivation is not strictly
followed out, it begins to breed in the spring on the wild food plants
and increases more and more until in August it has reached enormous
numbers. Before this the native plants are, many of them, either
matured or destroyed by the thrips, and as a result it spreads more
and more to the cultivated crops and trees that serve as hosts. Dur-
ing some years this occurs late in the season and very little real
damage results, but if this insect should begin the year in fairly large
numbers and under favorable conditions, great damage may result.
In Ventura County, in October, 1910, the author made a careful
examination of the entire bean-growing section and found that the
bean thrips occurred in extremely small numbers on the little vege-
tation remaining. At the same time it was extremely abundant
around Compton. This condition seemed to be a direct result of the
practice of the growers in Ventura of thoroughly plowing and culti-
vating the fields within a short time after the beans are harvested
and keeping them in perfect condition until the next crop is planted.
This advantage is increased because there is very little waste space
where weeds can grow up. Our investigations during the past two
years have shown that this insect is not abundant on cultivated crops
in the spring or early summer, but that after this period it increases i
more and more, and in certain years injures them so severely as to i
cause much loss. ;
NATURAL CONTROL.

RAINS.

One of the largest factors in the destruction of thrips in some
localities is the prevalence of hard, dashing rains. The author, ;
while working in Florida with the greenhouse thrips, once observed
CE E





NATURAL CONTROL.


that crotons, which in the greenhouse were infested with thousands
of thrips and which in June were placed outside and subjected to
the Florida summer rains, when examined in September were so free
from this insect that it was almost impossible to find specimens.
California, with its long dry season, does not obtain the same
benefit, but even there the rains may reduce attacks of the bean thrips
to some extent. On February 7, 1911, the writer observed a pea
field that had from 5 to 8 adults on every plant. After this date
there was a severe rain of several days' duration, and when the
field was again examined, on April 1, it was almost impossible to
find the thrips. Mr. Graf, writing from Puente, Cal., on October 6.
1911, noted that the larvme were much scarcer than a week earlier,
probably owing to a rainfall of one-half inch. Mr. Wildermuth,
at Tempe, Ariz., wrote on October 5, 1911:
A search in the patch of alfalfa back of the office, where thrips had been
very numerous for several weeks, failed to reveal very many thrips to-day.
The heavy rain of yesterday and last night was probably responsible for
washing them off.
In California, then, late rains in the spring may greatly diminish
the numbers of this insect, or early rains in the fall destroy many
that otherwise would enter hi-
bernation. : ....., ,


NATURAL ENEMIES.


FIG 4 b" e .1` ,' s .
Vir. 10.-The bean ihrips: Prepuppr parasit-


A great deal of attention has ized by Thripoctcnus rsselli. Much en-
been given to the subject of large. (Author's illustration.)
been gien to the subject of
natural enemies and some information obtained on this important
feature of insect control.
In the fall of 1910 the larva of this thrips was discovered to be
parasitized (see fig. 10) by a minute hymenopteron. This was de-
scribed by MAr. J. C. Crawford as Thripoctenus russelli (see fig. 11).
During 1911 this parasite was observed to work extensively in Los
Angeles County on the bean thrips and seemed to destroy large
numbers. Some collections of thrips larv,? gave as high as TO70 per
cent killed by the parasite. For a full account of this para-site the
reader is referred to Technical Series 23. Part II, Bureau of Ento-
mology, United States Department of Agriculture.
During 1911 the larva of a green lacewing fly (Chrysopa cali-
fornica Coq.) was commonly observed feeding on the larva of this
thrips. As this insect was observed so engaged in several localities
in Los Angeles County, and in noticeable numbers, it probably kills
a large number of thrips.
The larva of a syrphid fly (Sphcearophoria siph uripes Thomson)
was also observed on numerous occasions feeding on the larva of


41





THE BEAN THRIPS.


the bean thrips, and in confinement larvae were observed to kill and
eat large numbers of the host.
The young of Triphleps insidiosne Say were noticed on many
occasions feeding on the young of this thrips and undoubtedly aid
in reducing its numbers.
The larvae and adults of Hippodamia convergens Guer were fre-
quently collected on plants infested with thrips, where they were
busily engaged in feasting on the tender larvae of the bean thrips.
On several occasions larvae of a predaceous thrips, probably ,Eolo-
thrips fasciatus L., when collected were feeding on the larvae of the
bean thrips.


















I'".. 11.-A hym_ nopuerout parasite, '1hripocienmis rtnsmn ii: Adult. Greatly enlarged.
(Author's illustration.)
Mr. P. R. Jones informed the writer that at Lindsay, Cal., in
1910, lie found a nematode parasite working in the full-grown
larvw of the bean thrips."
A curious circumstance in connection with the observations made T
on the natural enemies of the bean thrips was the fact that in all of:
the predlaceous forms noted the alimentary tract became bright red,
undoubtedly due to the crimson or reddish pigmentation of the host.

ARTIFICIAL CONTROL.
CULTURAL METHODS.
In the case of crops planted over large areas and difficult or im-
possible to spray, such as beans, alfalfa, or cotton, cultural methods
offer the most hope as a remedy for the bean thrips. Where this
insect threatens injury it is recommended that these methods be used
so far as possible. It is very important that the crops be given


42






ARTIFICIAL CONTROL.


careful, clean cultivation, so that all weeds may be kept down in
the fields at all times, including the spring and fall. These same
weeds, especially the different species of wild lettuce, should be care-
fully destroyed along the edges of all fields and fence corners and
along the roads and railroad tracks. Cotton and beans should not
follow in old alfalfa fields if the latter were badly infested with the
bean thrips, and fields of these crops should be removed as far as
possible from the alfalfa fields. They should also be planted as
early as is consistent with good farming and encouraged by fre-
quent cultivations and fertilizers where necessary to produce an early
crop so as to escape the ravages of the bean thrips in the late summer.
As this insect feeds on such a variety of plants it is hardly pos-
sible that rotation of crops would aid materially in its control unless
some crop could be found that is quite immune.
Where it is injuring alfalfa Mr. Wildermuth recommends disking
and thorough renovation of the fields and good irrigation in order
to give the plants as much chance as possible to make a quick growth.

SPRAYING.

The control of this thrips by spraying is impracticable for a crop
such as alfalfa or cotton, and because of the low trailing vines of
the bean will probably be successful with this plant only when the
vines can be easily reached from the underside. In case injury to
fruit trees is threatened it can be controlled by using the spray so
successful against the pear thrips. This is a solution of 20 per cent
nicotine, diluted at the rate of 1 part to 60 parts of water in a 6
per cent distillate-oil emulsion.1
The distillate-oil stock emulsion, according to the formula of
Foster and Jones, is made as follows:
Hot water _--------------------------------------gallons-_ 12
Fish-oil or whale-oil soap_ ----------------------------------potiuds-_ 30
Distillate-oil (raw) 30 to 34 Baum6 -----------------------gallonss- 20
Have the water boiling hot when put into the spray tank and add the soap
immediately while the agitator is running at a good speed. When the soap is
all thoroughly dissolved pour in the oil slowly, keeping the mixture well agi-
tated while the oil is going into the tank. When all of the oil is in and well
mixed, pump out through the nozzles at good pressure (not less than 175
pounds) into storage tanks.
No one should attempt to make this stock emulsion without a power spraying
machine, as thorough agitation and high pressure are important requisites.
Also, care should be used in having measurements reasonably exact, the water
boiling hot, and the soap thoroughly dissolved before any oil is put in. This
stock solution contains approximately 55 per cent oil, and to make a 3 per cent
emulsion use 51 gallons of this stock in each 100-gallon tank.
1 For a full account of this spray as used against the pear thrips, see Circular 131,
Bureau of Entomology, U. S. Dept. of Agriculture, pp. 8-9.


43






44 THE BEAN THRIPS. I

A simpler formula and one that possibly will act quite as well on
this insect, where it is exposed on the foliage, and one that will offer
no chance for the burning of the foliage, has given good results in
the destruction of Heliothips rubrocirnctus Giard in Florida. Mr. "
Edward Simmonds, of the Bureau of Plant Industry, advised the '
writer that a solution composed of 1 gallon of blackleaf tobacco ex-
tract, 1 pound of whale-oil soap, and 50 gallons of water gave excel-
lent results in treating trees infested by this insect. This formula
seems a little strong to the writer and he would recommend using the
blackleaf at the rate of 1 part to 60 parts of water. In the place of
this. a 40 per cent solution of nicotine can be substituted at the rate
of 1 part to from 1.000 to 2,000 parts of water.

DISTRIBUTING THE PARASITE.

Possibly the parasite of this insect can be artificially distributed
with good results to sections infested by this thrips where the para-
site does not occur. For directions and methods of shipping this
parasite, the reader is refei red to Technical Series 23, Part, II, Bureau
of Entomology. U. S. Department of Agriculture, page 51.

BIBLIOGRAPHY.

1. IPERGANDE. THEODORE.-IUsect Life, vol. 7, pp. 391-392, 1895.
Original description of the species.
2. UZEL, J.-Mon. tier Ord. Thysau., p. 459. 1S95.
Copy of the original description of Pergande.
3. HINDS, W. E.-Proc. U. S. NYt. Mus., vol. 26, pp). 174-175. 190(2.
Redescription of single female.
4. DANIEL, S. M.-Ent. News. vol. 15, p. 294. 1904.
This author seems to have taken Pergande's records of locality and host
of this insect.
5i. DANIEL. S. M.-Ent. News, vol. 15, p. 297, 1904.
Described the male as a new species under the name Caliothrips woodworthi.
;. .[otI11boN. DuiDLEY.-Tech Ser. 12, Bur. Ent., U. S. Dept. Agr., pp. 39, 43,
a'. 5 I2. PI. II, figs. 12-14, 1907.
Records capture on orange, pea vines, and wild vetch and places CUiothripa
coodirorthi as a synonym of H. fasciatus.
7. C(RAwVFORlD. D. L.-Poimoua Journ. Eut.. vol. 1, pp. 120-121, 1909.
Records this species from pine foliage, Lotus r.laber, and blossom end of
ripe apple in southern California.
S. HREM.iNER. 0. E.-Destructive insects and their control. Hort.. 1910.
This thrips, under the name Euthrips fasciatus, was recorded as injuring
peas and beans and occurring on alfalfa and peach and pear trees.
9. ('OIT. J. ELIOT, and PACKARD, W. E.-Cal. Agr. Exp. Sta., Bul. 210, pp. 168.
184, 1911.
This thrips, under the name Heliiotlirips fascietus (sic), recorded as injuring -
alfalfa and cotton in the Imperial Valley, Cal.
10. MOULTON. DUDLEY.-Tech. Ser. 21, Bur. Eunt., U. S. Dept. Agr., pp. 9, 14, I
23-24. ,
Notes on synonymy and food plants. '
'.
:.:EE






BIBLIOGRAPHY. 45

I. KARNY, H.-Entomologisehe Rundscl;.aut. Jahrgang 2.. p. 180, 1911.
Revision of the genus Heliothrips, with table of species including fasciatus.
12. RUSSELL, H. M.-Proc. Ent. Soc. Wash., vol. 12. pp. 235-238, 1911.
A brief summary account of a parasite reared from Heliothrips fasciatus.
13. Ru'SSELL. H. M.-Tech. Ser. 23. Pt. II. Bur. Ent.. V. S. Dept. Agr.. pp. 2-.5-2.
1912.
A very full account of the life history and habits of the parasite reared from
this thrips.
14. MonzI., A. W.-Monthly Bul. State Hort. Comm. C.0l.. vol. 1, no. 5. p. 162.
April, 1912
Heliothrips fascidatus Perg. is noted a- one of the species affecting the
orange.















::tiI





























J... +r'

















... I i -

















INDEX.


,olothripsfasciatus, probable enemy of bean thrips...........
Alfalfa, food plant of bean thrips .............................
Apple, food plant of bean thrips ............................
crab, bean thrips taken thereon ......................
Atripler sp., food plant of bean thrips........................
Beans, food plant of bean thrips............................
Beets, sugar, food plant of bean thrips......................
table, food plant of bean thrips ......................
Bidens pilosa, food plant of bean thrips ......................
Cabbage, food plant of bean thrips- ...........................
Caliothrips iwoodworthi, bibliographic references...............
synonym of Heliothrips fascial hi ......
Cauliflower, food plant of bean thrips.........................
(Chenopodium murale, food plant of bean thrips.............
Chrysomphalus aurantii, association with bean thrips on orange
Chrysopa califonira, enemy of bean thrips..................
Cigarette flower, Chinese. (See Nicotiana glauca.)
Clover, burr', food plant of bean thrips .......................
Cotton, food plant of bean thrips............................
Crepsis (?) sp., food plant of bean thrips......................
Cultural methods in control of bean thrips....................
Distillate-oil emulsion against bean thrips ...................
Echinocystis, probable food plant of bean thrips .............
Erigeron canadensis, food plant of -bean thrips.............
Eunanus brevipes, food plant of bean thrips..................
Euryptera lucida, food plant of bean thrips....................
Euthripsfasciatus, bibliographic reference...................
= Heliothrips fascia(us.....................
pyri. (See Thrips, pear.)
Fish-oil soap. (See Soap, whale-oil.)
Gnaphalium californicum, food plant of bean thrips...........
Helianthus annuus, food plant of bean thrips................
Heliothripsfasciatus. (See Thrips, bean.)
hremorrhoidalis, larval habits....................
rubrocinctus, control by spraying.................
larn-al habits ........................
Heliotrope, wild. (See Hfeliotropium curassavicum.)
Heliotropium curassavicum, food plant of bean thrips.......
Hippodamia convergens, enemy of bean thrips.................
Lacewing fly, green. (See Chrysopa californica.)
Lactuca scariola. (See Lettuce, spiny wild.)
Lettuce, food plant of bean thrips .......................---.....
spiny wild, food plant of bean thrips................


Page.
...... 42
16, 17.28-30
..... 16,31


....leaf..........
leaf ............


... 16.17,


17
31
16,27
17.28
28
31
28
44
16
28
31
16
41

31
28-30
31
42-43
43
31
31
31
31
44
16


..... 31
..... 31

9
..... 44
9

..... 31
..... 42


..... 28
14.21.27.30





48 THE BEAN THRIP?


Lotus americanus, food plant of bean thrips .........
glaber, food plant of bean thrips...............
Mirabilis californica, food plant of bean thrips.......
Nasturtium. (See Tropieolum major.)
Nematode parasite, enemy of bean thrips ...........
Nicotiana glauca, food plant of bean thrips ..........
Nicotine solutions, against bean thrips .............
sulphate against bean thrips...............
Oil. (See Distillate oil and Soap, Whale-oil.)
Orange, food plant of bean thrips...................
Chrysomphalus aurantii.......
medium in dispersion of bean thrips ..---....
Parasite of bean thrips, artificial distribution ......
Peach, food plant of bean thrips ..................
Pea, food plant of bean thrips .....................


'3.


.... ... ... ... ... ... 16,831
0::



....... ................. 31
........................ 16


- - - - - - - . - - 1 1 6
........................ 31
. . .- .- .- .- . . . -. 4 2


........................ 316


........................ 15

........................ 16,31

..................... 14. 16, 3128
. . .. ... .. ... .. .. ... 14, 16, 28


wild. (See Lotus american us.)
Pear, food plant of bean thrips........................................... 16. 17, 28
Pine, food plant of bean thrips .............................................. 16
Polygonum aviculare, food plant of bean thrips ............................. 31
Poplar, tulip, bean thrips found thereon .................................... 31
Potato, food plant of bean thrips ............ ................................. 28
Radish, food plant of bean thrips........................................... 31
Rains in control of bean thrips.............................................. 40-41
Soap, whale-oil, and blackleaf tobacco extract against Heliothrips rubrocinctus


and bean thrips..


. .... .............................................. 44


Sonchus oleraceus, food plant of bean thrips..........................
Sphxrophoria suiphuripes, enemy of bean thrips ......................
Thcsonia mellissimnus, food plant of bean thrips.......................


Thistle, sow.


(See Sonchus oleraceus.)


Thripoctenus russelli, artificial distribution..................................
parasite of bean thrips .............................. 16,
Thrips, bean, adult female, description -................... ..................
habits...................... ...... ........ ............
male, description ........................................
adults, recently described, description ------......................
bibliography .................. ..................................
control, artificial ...................... ..........................
natural....................................... .......
description .................... ..................................
distribution ....................................................
egg, description........................... ...................
hatching................................................
stage, length at Compton, Cal............................
in Imperial Valley.........................
enemies, natural..........-..................----.- .............
feeding habits ..................................................
flight ........ .............................................-
food plants ..................................................
generations, number, at Compton, Cal.........................
habits of adult................................................
larva............................ .....................
prepupa and pupa.............-------............--......
hatching of eggs..............................................


31
41-42
31

44
41,42
9
17-23
10
10
44-45
42-44
40-42
8-9
14-16
10
23-05
31-32
37-38
41-42
20-21
21
27-31
37
17-23
23-26
26-27
23-25






INDEX.


Thrips, bean, hibernation ........................... ..........................
emergence therefrom, at Compton, Cal..............


entrance, at Compton, Cal..........
in navel end of orange .............
history......................... .............
injury, nature and extent......................
larva, first-stage, description ...................
habits...... ............................
molting ..................................
second-stage, description.................
larval period, length at Compton, Cal ....---.......-
in Imperial Valley .........
leaping.............. ..........................
length of life in- winter.........................
normal............................
life cycle, total length at Compton, Cal.........
mating, method................................
m olting of larva ................................
nymph, full grown. (See Thrips, bean, pupa.)
young. (See Thrips, bean, prepupa .)
occurrence, notes .............................
origin .........................................
oviposition, method and time...................
number of eggs deposited: ------..........-
period ............................
prepupa, description..........................
habits ...............................
prepupal period, length at Compton, C'al ........
in Imperial Valley-....
pupa, description..............................
habits ............ .......................
pupal period, length at Compton, Cal...........
in Imperial Valley........
recent records.............................
reproduction, kinds..............................
seasonal history at Compton, Cal................
Tempe, Ariz ................
in Imperial Valley .............
sexes, proportion ...............................
greenhouse. (See Heliothrips hxmnorrhoidh'.'s.)
pear, destructiveness in California .....--......-.........


Tobacco extract, blackleaf, and whale-oil soap, against I Heliothrips rubrocinctus
and bean thrips.........................................................
Tomato, food plant of bean thrips........................................
Triphleps insidiosus, enemy of bean thrips....................................
Tropaeolum major, food plant of bean thrips..................................
Tulip poplar, bean thrips found thereon .....................................
Turnip, wild, food plant of bean thrips....................................
Verbascum virgatum, food plant of bean thrips..............................
Vetch, wild, food plant of bean thrips.......................................
Whale-oil soap. (See Soap, whale-oil.)


49


Page.
39-40
36
36-37
15
16
8
10-11
23-26
25-26
11
32-34
38
22
22-23
22
36
17-18
25-26


40
14-16
18-19
19-20
19-20
12
26-27
34-35
38-39
13
26-27
34-35
38-39
16-17
20
31-37
39
37-39
20


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