Front Cover
 Table of Contents
 The family aleyrodidae
 Origin and distribution
 Life history and habits
 Methods of dissemination
 Effects of cold
 Food plants
 Character of injury: sooty...
 Natural enemies
 Fungous diseases
 Methods of introducing these fungous...
 How far may the fungus be trusted...
 Other sprays and remedies than...
 When to spray and what to use
 How to spray
 Scalding action of resin wash...
 The nursery situation
 Insects sometimes mistaken for...
 The outlook
 Summary of important facts and...
 The nearest relatives of white...
 The white fly and its allies

Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 67
Title: White fly
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00027699/00001
 Material Information
Title: White fly
Series Title: Bulletin - University of Florida Agricultural Experiment Station ; 67
Physical Description: Book
Language: English
Creator: Gossard, H. A.
Publisher: Florida Agricultural Experiment Station
Publication Date: 1903
 Record Information
Bibliographic ID: UF00027699
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Front Cover
        Page 595
        Page 596
    Table of Contents
        Page 597
        Page 598
        Page 599
    The family aleyrodidae
        Page 600
    Origin and distribution
        Page 600
        Page 601
        Page 602
        Page 603
        Page 604
        Page 605
        Page 606
        Page 607
        Page 608
        Page 609
        Page 610
        Page 611
    Life history and habits
        Page 612
        Page 613
        Page 614
        Page 615
        Page 616
    Methods of dissemination
        Page 617
    Effects of cold
        Page 618
        Page 619
    Food plants
        Page 620
    Character of injury: sooty mold
        Page 621
        Page 622
        Page 623
    Natural enemies
        Page 624
    Fungous diseases
        Page 625
        Page 626
        Page 627
    Methods of introducing these fungous diseases into infested groves
        Page 628
        Page 629
        Page 630
    How far may the fungus be trusted to destroy the fly?
        Page 631
        Page 632
        Page 633
        Page 634
        Page 635
        Page 636
    Other sprays and remedies than resin wash
        Page 637
        Page 638
        Page 639
    When to spray and what to use
        Page 640
    How to spray
        Page 641
        Page 642
        Page 643
        Page 644
        Page 645
        Page 646
    Scalding action of resin wash explained
        Page 647
        Page 648
        Page 649
        Page 650
        Page 651
        Page 652
        Page 653
        Page 654
        Page 655
    The nursery situation
        Page 656
        Page 657
        Page 658
        Page 659
        Page 660
        Page 661
        Page 662
        Page 663
        Page 664
    Insects sometimes mistaken for white fly
        Page 665
        Page 666
    The outlook
        Page 667
        Page 668
        Page 669
    Summary of important facts and recommendations
        Page 669
        Page 670
    The nearest relatives of white fly
        Page 671
    The white fly and its allies
        Page 672
        Page 673
        Page 674
        Page 675
        Page 676
        Page 677
Full Text


(Aleyrodes citri.)


The bulletins of this Station will be sent free to any address in Florida upon applica-
tion to the Director of the Experiment Station, Lake City, Fla.

DeLand, Fla.:


JUNE, 1903.


GEO. W. WILSON, President ................. Jacksonville.
F. E. HARRIS, Vice-President .................... .Ocala.
J. D. CALLAWAY, Secretary .... ........... ..Lake City.
C. A. CARSON, Chairman Executive Committee, Kissimmee.
J. R. PARROTT ............................ Jacksonville.
E. D. BEGGS ............ ..... ...... .........Pensacola.
L. HARRISON.......... ......... ......... .... Lake City.


T. H. TALIAFERRO, C. E., Ph. D ................ Director.
H. K. MILLER, M. S............ Vice-Director and Chemist.
H. A. GOSSARD, M. S..................... Entomologist.
H. H. HUME, B. Agr., M. S.. .. Botanist and Horticulturist.
CHAS. F. DAWSON, M. D., D. V. S.......... Veterinarian.
*C. M, CONNER, B. S..................... Agriculturist.
A. W. BLAIR, M. A............... .. .Assistant Chemist.
LUCIA MCCULLOCH, B. S., Asst. Biologist and Asst. Librarian.
W. P. JERNIGAN ................ Auditor and Bookkeeper.
A. L. GLAYTON .............. ..Stenographer and Librarian.
JOHN H. JEFFERIES. Gardener in Horticultural Department.
Louis DEGOTTRAU, Supt. Citrus Experiments at Boca Raton.

*Supt. Farmers' Institutes.


Introduction ...... ...... ...... ...... ...... 599
The Family Aleyrodidae ............ .... ....... 600
Origin and Distribution .................. .. .... 600
Description .......... ..... .. ...... ...... 604
Life History and Habits .................. ...... 608
Methods of Dissemination ............ ..... ..... 613
Effect of Cold ..... ..... ...... ...... ...... .. 614
F ood P lants ...... ...... ...... ...... ...... .... 616
Character of Injury. Sooty Mold ................... 617
Natural Enemies .................. ............ 620
Fungous Diseases ............ .................. 621
Methods of Introducing Fungous Diseases into Infested
Groves. ..... ............................ 624
How Far May the Fungus be Trusted ? ............... 625
Sprays ...... .......... ............ ...... 628
Other Sprays than Resin Wash, ................... .. 631
When to Spray and What to Use ...... ............ 634
How to Spray ...... .... ...... ..... ........ 635
Scalding of Resin Wash Explained, ................... 641
Fumigation ...... .................. .......... 643
The Nursery Situatidn .................. ...... .. 650
Insects Sometimes Mistaken for White Fly, .......... 655
The Outlook ...... .................. .......... 657
Acknowledgements, ................. ............. .659
Summary of Important Facts and Recommendations... 659
The Nearest Relatives of the White Fly (By Prof. T. D.
A. Cockrell)...... .................. ...... 661

The White Fly.

Aleyrodes citri Riley & Howard.

This insect first attracted the notice of entomologists in
1878, when it was observed in the orangery of the U. S.
Dept. of Agriculture at Washington. Some observations were
made upon its life history during that summer but no descrip-
tion of the insect was published until 1885 when Mr. W. H.
Ashmead furnished a meagre description in the Florida Dis-
patch, Vol. XI, new series. The first adequate description
was given by Riley & Howard in Insect Life, Vol. V, No. 4,
issued in April, 1893. The name which Mr. Ashmead had
bestowed, Aleyrodes citri, was retained by Riley & Howard,
the insufficient description being discarded. The next impor-
tant contribution to the literature of the insect was by Prof. H.
J. Webber in an issue from the U. S. Division of Vegetable
Physiology and Pathology in 1897. Prof. Webber's pamphlet
was entitled Sootv Mold of the Orange and its Treatment;
but it recognized sooty mold as a development resulting from
white fly attack. Prof. Webber's recommendations pointed
out the necessity for destroying the fly, it being the cause of the
mold, and the article was a very important one because it first
emphasized the efficacy of resin spray against the insect and
also described the two fungous diseases that constitute the
greatest natural checks upon its multiplication.
The most extensive work with hydrocyanic acid gas
against the insect in the field was performed by the writer
about two years ago, a summary of which was published in the
annual report of the Experiment Station for the same year.


The Family Aleyrodidae.

The family Aleyrodidae, to which the white fly belongs,
contains a large number of species, most of which are of little
economic importance, usually being kept in good subjection
by minute hymenopterous parasites. Among the exceptions
to the general statement of harmlessness is a European
species, A. vaporariorum, which has long been known as some-
thing of a pest in Europe; and in this country, relieved of its
European parasites, it is all too fast getting the reputation of
being a first-class pest in greenhouses and gardens. The white
fly of the Melon Papaw (Carica papaya) Aleyrodes variabilis is
also a pest that is not to be despised when on papaw; but owing
to the restricted cultivation of its host it will not attract great
attention unless it should prove its ability to multiply on other
and important crops. The orange white fly, Aleyrodes citri, is
the most destructive insect of the family. The family is charac-
teristic of the tropics, but some species thrive out of doors in the
northernmost parts of the United States. The immature
insects are very scale-like, being closely related to the Coc-
cidae or family of scales. The most conspicuous character sepa-
rating the two families is that both sexes of adult Aleyrodidae
possess two pairs of wings and can fly, while only the males of
the Coccidae are motile and are possessed of a single pair of

Origin and Distribution.

The original home of the white fly is not definitely known.
Some entomologists incline to the belief that it is a native of
Florida, others think it an importation. I submit at the conclu-
sion of the bulletin an interesting contribution from Prof. T. D.
A. Cockerell, who believes, from a comparative anatomical
study of A. citri and many other species which he has collected
from various parts of the world through many years, that our
pest belongs to an Asiatic or Australasian group of white flies,
and hence is not native. On the other hand, Prof. A. L.


The Family Aleyrodidae.

The family Aleyrodidae, to which the white fly belongs,
contains a large number of species, most of which are of little
economic importance, usually being kept in good subjection
by minute hymenopterous parasites. Among the exceptions
to the general statement of harmlessness is a European
species, A. vaporariorum, which has long been known as some-
thing of a pest in Europe; and in this country, relieved of its
European parasites, it is all too fast getting the reputation of
being a first-class pest in greenhouses and gardens. The white
fly of the Melon Papaw (Carica papaya) Aleyrodes variabilis is
also a pest that is not to be despised when on papaw; but owing
to the restricted cultivation of its host it will not attract great
attention unless it should prove its ability to multiply on other
and important crops. The orange white fly, Aleyrodes citri, is
the most destructive insect of the family. The family is charac-
teristic of the tropics, but some species thrive out of doors in the
northernmost parts of the United States. The immature
insects are very scale-like, being closely related to the Coc-
cidae or family of scales. The most conspicuous character sepa-
rating the two families is that both sexes of adult Aleyrodidae
possess two pairs of wings and can fly, while only the males of
the Coccidae are motile and are possessed of a single pair of

Origin and Distribution.

The original home of the white fly is not definitely known.
Some entomologists incline to the belief that it is a native of
Florida, others think it an importation. I submit at the conclu-
sion of the bulletin an interesting contribution from Prof. T. D.
A. Cockerell, who believes, from a comparative anatomical
study of A. citri and many other species which he has collected
from various parts of the world through many years, that our
pest belongs to an Asiatic or Australasian group of white flies,
and hence is not native. On the other hand, Prof. A. L.


Quaintance, who has made a specialty of the family, believes
it quite probable that the insect is native, giving as his chief
reason for so thinking that he has found it on Viburnum nudum
and occasionally on Quercus aquatica in primeval hammock
many miles from an orange grove; the conditions under which
he has found it on the former plant in dense hammocks particu-
larly emphasize to his judgment the possibility of its being
indigenous to Florida. An instance of orange infestation
which, I think, might be considered as sustaining Prof. Quain-
tance's view is found in the Manatee river section. The insect's
first appearance in this district was in the Foster grove near
Manatee. I am informed that not a bud or plant of any descrip-
tion was permitted to come upon this place from abroad for
some years before the fly appeared. Did it migrate to the
oranges from a native plant in the dense woods surrounding
the grove? Or, did some one of the tens of thousands of migrat-
ing birds from the upper part of the State get some of the newly
hatched insects entangled in its feathers and carry them to trhe
Foster grove? Or again, might the calculating eye of a con-
scienceless competitor from upper Florida have feared the rich
promise held out to the settlers in the Manatee region by the
vigorous grove of Mr. Foster and have chosen to equalize the
race between the respective sections by a malicious infection
before the stress of competition was felt? Or what is, perhaps,
more probable, is there some mistake about the report that no
plants were introduced from abroad? However these ques-
tions may be answered, I incline to the view that the white
fly is an imported insect. It is very unusual for an insect as vul-
nerable to parasitic attack as white fly to multiply in such
excessive numbers. I have found A. floridensis on orange at
Candler, but very sparsely, and the same insect has been sent
to me from Arcadia. Such native species rarely become trouble-
some, it being well known that hymenopterous parasites usually
keep them in subjection. The history and spread of Aleyrodes
vaporariorrum, a species known to have been imported, appar-
ently exactly parallels that of A. citri. Few indeed are the
insect enemies of the orange white fly; I have observed none

602 BULLETIN NO. 67.

except lace-wing larvae and some mites and these scarcely
deserve mention, they make so little impression on the insect.
It may be possible to explain the spread of the fly as a native
insect without its being accompanied by parasites by paralleling
it with the Colorado potato beetle, a native insect originally
feeding in restricted numbers upon a wild Solanaceous planif
in Colorado and outstripping all of its enemies in a march to
the Atlantic Seaboard as soon as the potato patches of the
settlers furnished it with a suitable food plant outside of its
original habitat; but if such were the case with white fly, would
not some parasites ere this have made themselves known in
some quarter of the infested territory? While Mr. Marlatt of
the U. S. Dept. of Agriculture was in China and Japan hunting
for the home of San Jose scale he collected some species of
Aleyrodes but A. citri was not among them. Mr. E. Ernest
Green has not collected A. citri in Ceylon, nor has Mr. H. W.
Peal of Calcutta found it in Bengal. Mr. H. Maxwell Le-Froy,
of the Imperial Dept. of Agriculture of the West Indies, has
not found it in the West Indies, though another species of Aley-
rodes is a pest upon the orange in Antigua. Importations
of citrus plants have been made from time to time from China,
Japan, and other parts of the East; and also thirty or forty
years ago some large wholesale importations were made from
Brazil, suggesting that it may have originated in the American
tropics. Mr. Alexander Craw of the California State Board of
Horticulture writes that he has received the insect upon plants
from Chili where it is a great orange pest.
The fly seems to have been first known in Florida through-
out the region comprised in Volusia, Marion, Lake, Alachua,
and Orange counties from which, I have little or no doubt,
it was transferred to the Manatee country and to local centers
along the northern border of the State. Following the severe
freezes during the years from 1895 to 1900 the insect was so
thoroughly exterminated in the northern part of its range by
successive defoliations due to cold that it was believed to be
extinct throughout the section, and for all practical purposes
was so. However, during the past two seasons there have been


indications of a revival in local spots, some of these, when
upon oranges, being so conspicuously adjacent to hammocks as
to suggest that the insects emerged from them. The nurseries,
which for some years have furnished a supply of clean stock,
are now becoming threatened and, while with proper care on
the part of the nurserymen. I believe clean stock can vet be
supplied for several years to come, the time is already here
when the buyer must depend upon the representations and
reliability of the respective nurserymen to guide him and not
upon the inspections of the Entomologist. Certificates of free-
dom from the pest, correct when issued, may become untrue
before their expiration, a year after being given; hence I can
assume no further responsibility toward restricting its spread
by inspection work. -
In some of the southern counties it is found in a majority
of the groves, but there is probably no county that does not
possess many trees which are not vet infested. Manatee county
is perhaps in the worst condition of any, at least 75 per cent.
of the groves being infested. There are spots of infestation
in Polk, Lee. Hillsboro, Marion, Putnam, Alachua, and
Orange counties: it is also established at three or four points
on the East Coast railroad in the counties of Duval, Volusia
and Brevard; and in local spots in Baker, Columbia, Jefferson
and Leon counties. It doubtless occurs at many places of which
I have no record. I have no resources at my command to make
a general inspection of the entire State, and correspondents
sometimes seem disposed to conceal the fact that it is in their
neighborhood. From information based upon its acknowledged
distribution before the freeze of 1895 and letters on file in my
office I conclude that a general and thorough State inspection
would probably discover it in Lake. Osceola, DeSoto, Sumter
and Pasco counties at least.
Outside of Florida the insect is recorded as either now
being or having once been in Louisiana, Georgia, North Caro-
lina, District of Columbia, and Texas. California newspaper
reports sometime since indicated that some insect resembling
Aleyrodes citri was present in the neighborhood of Los Angeles,


but the horticultural officers of that state seem to be confident
that it is not present, and it is probable that with the thorough
methods of warfare there employed, coupled with climatic
influences, the insect would not attract much notice. The
orange districts of Louisiana are quite generally infested, the
insect probably having been introduced at the time of the New
Orleans exposition in 1895. The white fly is often mentioned
in connection with greenhouse infestation but here there may
easily be confusion of specific identities.

THE EGG.-Very minute, about 1-125 of an inch (o.2mm)
in length, being attached to the leaf by a slender stem or foot-
stalk; about four times as long as thick, widest just beyond
the middle towards the free end; color pale yellow, when first
laid tinged with greenish, becoming darker as the embryo
develops and some specimens becoming of a dark steel grey
or blue. Surface smooth and shiny, often with clinging par-
ticles of white wax. Red eyes of embryo conspicuous through
the shell as it approaches maturity.
LARVA.-Passes through four moults before reaching the
pupa stage. When first hatched the insect is about 1-8o of an
inch in length (o.3mm), of a pale greenish yellow color with
two darker yellow spots on the back of the abdomen. There are
four conspicuously long bristles at the posterior part of the
body and six long ones on the anterior end with minute ones
along the sides, each arising from a tubercle. Antennae, three
or four jointed. Four eyes, dark reddish. Legs short, six in
number. Mouth parts consist of a long, sucking tube. On
the dorsal side of the last abdominal segment is a subovate,
brown colored opening, the vasiform orifice. Appearance in
second and third stage not markedly different from the first
except in size and minute microscopical characters. in the
fourth stage the length has increased to about 6-ioo of an inch
(I.5mm), the width to 4-1oo of an inch (imm) and the con-
spicuous bristles have vanished; a pair of persistent minute


bristles is found on the anterior border, one on each side, and
another pair, also minute, is disposed one on each side of the
anal cleft. The insect is very flat and close pressed to the
leaf; the dorsum or back is crossed by twelve transverse ridges
indicating the segments. Arising from the prothoracic region
on each side, extending obliquely outward and forward to the
margin is a distinct ridge or fold, the breathing fold. The out-
line of the developing wings of the embryo can be distinctly
seen from the first.
PUPA.-To ordinary observation quite similar to the
fourth larval stage but more plump and of thicker body;
broadly oval. Measurements about as in fourth stage, slightly
narrower. A broad, deep orange or coral-red spot on the back
near anterior end of abdomen; eyes purplish; vasiform opening
and ring brown; transverse ridges on abdomen shorter and less
distinct than in last larval stage.
ADULT.-Female: Length slightly over 1-2o of an inch
(I.4mm) ; wing expanse about twice the body's length (2.8-
mm) ; color light orange yellow; the rostrum or beak is tipped
with black; the wings are colorless when newly hatched, but
within two or three hours become covered with a fine white
wax, hence, the name "mealy-wing" sometimes given to the in-
sect. The body also becomes covered with more or less of wax
but its ground color is not wholly obscured. Tarsi two-jointed.
The eyes, reddish-brown in color, are each divided into two
parts by a curved ridge projecting from the cheek, the upper
divisions being the smaller. Ovipositor short, retractile.
ADULT.-Male: The male resembles the female but is smaller
with the head and abdomen having heavier tufts of adhering
wax. The abdomen is more slender and has at its termination
a pair of claspers slightly curved upwards.



Aleyrodes citri.
Fig. I-Adult female ,with expanded wings, much enlarged.
Fig. 2.-Adult female, with wings folded over the body in normal
roof-like position.
Fig. 3.-Egg and foot-stalk of same, greatly magnified.
Fig. 4.-Egg-shell, showing the split through which the larva emer-
Fig. 5.-Tip of male abdomen, showing claspers.
Fig. 6.-Antenna, showing annulated joints.
Fig. 7.-Fore margin of front wing.

Fig. 8.-Larva of Aleyrodes floridensis greatly magnified.
Fig. io.-Greatly enlarged section of waxen fringe, surrounding A.
Fig. II.-Outline of larva of Lecuniun hesperidnu.

7 ,
/- -








'.; (, 7







Alevrodcs citri.

Fig. I.-Larva, fist stage, greatly magnified.
Fig. 2.-Larva, first stage, drawn to same scale as figures 3, 4, 5, 8, 9,
and io.
Fig. 3.-Larva, second stage.
Fig. 4.-Larva, third stage.
Fig. 5.-Larva, fourth stage.
Fig. 6.-Margin of advanced larva, greatly enlarged.
Fig. 7.-Vasiform orifice of fourth larval stage, showing crenulated
operculum with lingua in the center
Fig. 8.-Pupa, showing embryo and distribution of orange colored
areas. Waxen tufts extending from the breathing tubes are shown.
Fig. 9.-Adult, with folded wings, emerging from the pupa case.
Fig. io.-Empty pupa case, showing split through which the fly


Life History and Habits.
FIRST BROOD OF ADULTS.-The first brood of adults issue
during March, April and early May. The date varies with
the season and locality. Localities not over a quarter of a mile
from each other may exhibit a variation of two or three weeks,
and particular spots or plants in an infested area may furnish
an anticipation of the general appearance of the brood by a
long interval. Thus, some sheltered lemon bushes at Ellenton,
Fla., were observed by the writer to have produced adults on
the IIth of February, though for the neighborhood at large
the bulk of the brood issued during March and April. At
Tampa, thirty to forty miles north of the Manatee section, the
spring brood of flies has in some seasons preceded their appear-
ance about Braidentown and Manatee by two weeks. Mr. A.
J. Pettigrew, a close observer at Manatee, says that he once
observed a few hatch about the 28th of January, and that he has
twice seen them appear in considerable numbers in February,
but that March hatches the bulk of the brood, most of them
being on the wing before April Ist. At Lake City, last year,
the few infested bushes about the town showed the first adults
about the 14th of April and hatching continued until late May,
most of them appearing during the last half of April. There
was several days difference in the dates of appearance upon
the different bushes. The present year found some of the adults
on the wing at Lake City March 12, and they were reported on
the wing at Orlando and at Palmetto on the 6th of March. At
Lake City only a few stragglers were observed after the middle
of April. Speaking of the entire district in which the insect
can exist from South Florida to Georgia, the bulk of the first
brood may be said to appear during March and April, with the
adults which have hibernated as half-grown larvae straggling
along into May and June. Only in the northern section will
they ever linger as late as June. The adults live from three or
four days to three weeks, the average period being from four
to seven days.
The adults love close-planted, sheltered groves into which


the winds enter with difficulty. Consequently, the insect never
becomes so numerous in well spaced, open groves on high pine
land as in thick-planted, unpruned groves on hammock land
surrounded by thick woods.
PAIRING AND EGG-LAYING.-The courtship of white fly,
as observed with a pair in confinement, is quite curious. The
male showed evidence of having detected the presence of the
unimpregnated female at a distance of one-fourth of an inch
or more, and approached her nervously, stopping at intervals,
especially as the distance was lessened, and swinging his body
about excitedly in a semi-circle, the head being used as a pivot,
his wings in the meanwhile opening and closing spasmodically.
While no movement was made by the female, several retreats
were made and she was repeatedly approached from many
directions before coition occurred. Upon the trees the males
and females rest side by side and two males, one on either
side, may often be seen giving their attentions to the same
Egg-laying begins within eighteen to thirty hours after the
adults issue when the weather is warm, (sixty-five to seventy-
five degrees) but with damp, cool weather several days may
elapse before they are deposited. Egg deposition occurs upon
the under surface of the leaves, preferably upon new ones,
especially those of water sprouts, but old leaves may also be well
covered with them; they are usually scattered over the irface
of the leaf without much order of arrangement but sometimes
are laid in the arc of a circle. From four to ten eggs may be
observed in such an arc and are so placed by the female using
her beak as a pivot around which the body is swung during
oviposition. The eggs are not as numerous, ordinarily, near
the edge of the leaf as further inward. Each female deposits
from seventeen to twenty-five eggs in breeding cages, the rate
of laying doubtless being governed by temperature. With
the thermometer at 70 degrees to 76 degrees F. for several
hours on each of two successive days the eggs were all laid
within twenty-four hours after the first one was deposited and


the females under observation died soon after they stopped lay-
By mathematical computation a leaf from young orange,
five inches long and two and one-half inches wide in the mid-
dle, collected at Myers, June 22, 1901, had upon it upwards
of 20,000 eggs. While so many eggs upon such a space is
beyond the average, it is by no means rare, and I have some-
times seen the number exceeded.
Hatching occurs in from three to twenty days according
to the weather. In the summer season when the temperature
maintains itself at from 80 degrees to 95 degrees for several
days together the eggs hatch in three or four days. Hatching
throughout the summer is very regular, comparatively speak-
ing, the range probably being from three to eight days, while
in spring and fall with temperature ranging from 50 degrees
to 70 degrees from two to three weeks is required. The egg
becomes of a metallic bluish-grey color as the embryo matures
and splits longitudinally for a short distance down both sides
at the distal end to give exit for the young larva.
motile and crawls about over the leaves and twigs for several
hours like a young scale before it attaches itself to the leaf. The
first molt occurs in from seven to twenty-five days according
to the temperature. In moulting, the larva bends the abdomen
upward at a right angle to the leaf surface and with slow,
struggling movement alternately raises and lowers it, the body
meanwhile shrinking from the interior of the skin, causing
the dorsal ridge to become distinctly elevated. The skin now
splits at the anterior end or beneath the head and by abdominal
wriggling the insect gradually pushes it off. The cast skin is
very thin and fragile and is blown away by the wind or drops
to the ground, seldom remaining long upon the leaf. The
periods between all the moults seem to be determined by temper-
ature and the fifth or pupal molt occurs in from twenty to thirty
days after hatching during July and August but requires from
four to five months during the winter. Add from ten to thirty
days as thie pupaT stage and the life cycle from egg to adult is



seen to range from forty or fifty days to six months. When
the insect is ready to emerge from the pupa shell, the skin splits
in the form of a cross beginning at the head of the larva and
extending along the middle of the back to the front of the abdo-
men where it bisects at right angles a transverse slit extending
to the margin on either side. The thorax of the fly comes out
first, followed by the head. The wings are much folded and
colorless when first exposed; the insect at once elevates them
into a vertical position to dry, and in about fifteen minutes they
are expanded and lowered to a horizontal position; in ten min-
utes more they are in their normal roof-like position over the
back; about two hours elapse before they lose their transparency
and commence to whiten, and five or six hours pass before the
typical powdery white appearance is reached.
The larvae attach themselves to the under sides of the
leaves and are inconspicuous because of their transparency and
greenish tinge. If the leaf be so doubled in the hand that air
is admitted beneath the insect, it at once becomes readily seen
and is translucent whitish green, spotted with orange. When
infestation is so excessive that the larvae overlap each other,
many of those that are beneath do not succeed in emerging,
especially if the head of the larva is the part covered. So far
as observed by the writer the larvae do not settle and feed else-
where than upon the leaves. While some reliable observers
report having found them attached to twigs and in buds. the
most diligent search has never revealed to me a single specimen
so located. Is it possible that the immature stages of one of the
Lecaniums (possibly hesperidum) have been mistaken for
white fly by the observers mentioned ?
Seen best from the ventral side of the larva but also visible
through the transparent dorsal surface, along the median line
and slightly forward of a line connecting the inner points of the
breathing folds, is a pulsating organ connected with the circu-
lation which beats from one hundred-twenty to one hundred-
fifty times per minute. Along the back of the abdomen the slow
pulsations of the heart proper, a long muscular tube, can often
be observed with a fairly good microscope. Absence of visible

Bul. 68-2

612 BULLETIN NO. 67.

movement in these organs may not be interpreted as perfect
proof of death but they often furnish positive proof when death
has not occurred and thus are a valuable means of observation
to determine what has been the effect of insecticidal treat-
SUMMER AND FALL BROODS.-During June and July the
second brood of adults are on the wing in the southern part of
the State, appearing about two weeks later in the latitude of
Lake City. At the latter place last summer they commenced
appearing about the first of July and were still abundant on the
12th of August. From this time onward there was no date
until the middle of November when every stage of white fly
from egg to adult could not be found in the neighborhood; not
always every stage upon the same bush but persistent search
was sure to find it within a half mile. September seemed to
bring the greatest number of adults, which, with early October,
may be regarded as the maturing time for the third brood.
This year the second brood commenced hatching at Lake City,
during the first week in June, and were reported to be hatched
and in full swarm at Micanopy at the same time. The second
brood, like the first, seems to be a month earlier this year than
While three generations a year seems to be the rule, there
is a tendency to continuous breeding as some adults were
observed upon privet at Lake City on Christmas day, and Prof.
H. A. Morgan has likewise observed that it issues upon warm
winter days in Louisiana. Four generations a year doubtless
occur often, but not in sufficient numbers to obscure three well
defined broods as the rule. Mr. Pettigrew sums up the history
of the adult as follows for Manatee: "The spring brood is in
sight from three to four weeks, then none are visible for three
or four weeks; the second crop is in sight four to five weeks
with one or two weeks following without any, after which the
broods run together so there is only a thick and a thin streak.
Sometimes the eggs for the winter brood of larvae are all
deposited in October and at other times nearly all in Novem-
All the eggs of the winter brood are hatched before Christ-


mas. By March st a few of the insects are pupae and there are
none that have not reached the third stage. The rapid develop-
ment of the belated larvae during the warm days of March and
April enable them to issue as adults within a month after the
first flies of the brood appear, so the first brood is well defined
each year. Something like ten to fifteen per cent. of the winter
brood die. before spring, at Lake City, from no very definite
Methods of Dissemination.
The insect is not a strong flyer but can go considerable
distances with the wind, and infected neighborhoods often fur-
nish unmistakable examples of the influence of prevailing winds
in scattering it. The flies are often found in clouds upon weeds
and herbage by roadsides and covered vehicles may collect
some of them under such circumstances and transport them
to considerable distances. They have also been observed upon
windows in railway coaches, indicating that they can be carried
long distances in this way.
I have stood beneath a tree upon which adults were plenti-
ful and had them alight upon my clothing; I have then walked
nearly a half mile against a stiff breeze and picked the flies
from me by the dozen at the termination of my journey. They
cling tenaciously to their support in a stiff wind but take
flight quickly in quiet air.
When newly hatched they crawl about like young scales
and may be caught in the hair of horses brushing against the
trees, or in the feathers of birds and be thus transported from
one grove to another.
During the months from July to December young larvae
as well as adults are apt to be present in small numbers, at
least, without intermission in an infested grove. Pickers, teams,
ladders, baskets, etc., going from an infested grove to a clean
one during this time can become the means of transporting the
pest as well as when the spring brood is hatching and flying.
Infested nursery stock is most apt to carry the insect into new

614 BULLETIN NO. 67.

Effects of Cold.

The larvae can stand more cold than the orange. I have,
in repeated instances, taken larvae from leaves that had fallen
to the ground because of cold ranging from 22 degrees to 17
degrees above zero, ten days to two weeks after the cold
occurred and found by microscopic examination that the pulse
was beating regular and strong. If infested leaves drop in
early winter the larvae doubtless perish as they invariably die
upon detached drying leaves in the laboratory in from nine
to fourteen days, but with leaves dropped in February and
lying upon moist earth it is conceivable that some of the insects
may mature and issue. It seems certain that white fly will
eventually range as far north as the hardiest orange. It will
also be able to perpetuate itself upon the more hardy of its food
plants, despite freezes that kill oranges to the ground.
To determine the degree of sudden cold which the insects
can survive, Mr.A. 0. Mann of the Lake City Ice Factory gave
me the freedom of his factory for experimental purposes and
sunk an empty can into the brine for my use. The temperature of
the brine ranged from Io degrees to 20 degrees, and the ther-
mometers kept suspended in the can recorded temperatures as
shown in the table. Twigs of orange and Cape jessamine, hav-
ing upon them well matured pupae of the fly were used April
12th and I4th as follows:

Time in Can Temperature readings in Result
ca;n tialen at intervals.
Experiment No. ....... 30 mill. 14 degrees, 15 de, 15 te A few snrvired and
issued as adults the
next day.
Experiment No. 2.... 1 hr 12 de., 14 de., 15 de., 15 de., All killed.
12 de., 14 de.

In the following experiments the pupae were prepared for
the extreme temperatures by first being put in cold storage.
The temperature in the cold storage room was from 48 degrees
to 50 degrees. Pupae left in this temperature for 48 hours
were apparently uninjured and adults continued to issue in the


cold storage room: but if any significance at all can be attached
to the cold storage preparation it weakens the resisting power
of the insects at this date as shown in the following experi-
ments :

Time in Coldl

ExperimentNo.3 1 hr. 45 min. 0

Experiment No. 4 48 hri. 30
Experiment No. 1 hr. 45 min, 1 h
Experiment No. 6 1 hr, 45 min. 2 h
Experiment No. 7 48 hrs. 2 i

Time Temperature read-
in can wings, by degrees,
in cans.

min. 12, 14, 15.

min. 25, 20, 20, 18.
r. 12. 14, 15, 12.
rs. 12, 14, 15. 15, 12, 10.
rs. 30 rin. 20, 20, 14, 12, 10.

Two flies issued,
remainder killed.
All killed.
All killed,
All killed.
All killed.

It is quite probable that had the experiment been per-
formed during the winter months with larvae that had become
accustomed to cold there would have been a larger percentage
of surviving insects. Temperatures as low as those used are
never reached in South Florida and seldom last for more than
a few minutes in North Florida: and when reached in a given
district there are always sheltered spots in which the mercury
does not fall so low. At various points along the line of the
Seaboard Air Line R. R. from Jacksonville to Tallahassee the
mercury has at different times, during the past ten years,
descended to 6 degrees and Io degrees. The fly, after such
freezes, has disappeared from sight for a time but has invariably
reappeared showing its ability to withstand the most extreme
cold lhat occurs in this latitude. However, it is apparent that
a deciduous orange adapted to North Florida and Georgia
would not suffer much from the fly.
Mr. A. J. Mitchell, Section Director of the Florida
Weather Service furnishes the following records for lowest
temperatures at three points near the northern boundary:


14 degrees, Feb. 8. 1895.
14 degrees, Dec. 29. 1691.
10 degrees. Feb. 13, 1899


15 degrees, Feb S, 1895.
16 degrees, Feb 18. 1900.
I' degrees, Feb. 13. 1899.


11 degrees, Feb. 8, 1895.
12 degrees, Dec. 29, 1894.
-2 degree. Feb. 13. 1899.



About two years after the 1899 freeze the insect was again
observed at Lake City. It was reported from Jacksonville at
about the same time.
State Chemist R. E. Rose informs me that the insect is
present in considerable numbers at Tallahassee, and my office
records show that it was present there before 1895.

Food Plants.

White fly occurs upon all varieties of citrus. C. trifoliata
is, of course, only infested during the summer months, being
a deciduous variety. The deciduous character of some of the
C. trifoliata hybrids will tend to retard the multiplication of the
pest upon them. The kumquat is still less a favorite than the
pomelo, and the latter, though often badly infested, is usually
attacked only after the adjacent oranges are overstocked. The
adult flies as well as the larvae sap the leaves and their taste
for certain varieties leads them to oviposit jon these when possi-
ble, going to less favored plants only as they are driven by
necessity to do so. Besides citrus, the Chinaberry tree (Melia
azederach) and Viburnum nudum the Cape jessamine (Gar-
denia forida), the Japan persimmon (Diospyros kaki), Cali-
fornia privet (Ligustrum amurense), Golden privet (Ligus-
trum sp.) and Mock Orange (Prunus Caroliniana)are food
plants. Various species of Ficus are said to be food plants; I
have seen it on two species, F. altissima, and on an unknown
species introduced from Costa Rica.
The water oak (Quercus aquatica) is occasionally infested,
according to Quaintance, and I have taken two or three larvae
advanced to third and fourth stage on scrub palmetto. Their
presence upon the latter plant is very rare having been observed
but once, though opportunities have been plentiful.
Prickly ash (Xanthoxylum sp.) is reported as a food plant
upon Jhat I consider to be reliable authority, but I have not per-
sonally seen the insect upon any one of the three species found
in this State.


SCharacter of Injury. Sooty Mold.

The injury caused by white fly is not as threatening to the
life of the tree as that caused by scale insects. The latter kill
branches and sometimes entire trees with great rapidity when
associated with other ailments, but their destruction by the
former is comparatively slow. White fly certainly does often
kill branches and sometimes trees, but rarely does a tree die
from its attack alone. Footrot, dieback, and kindred troubles
are the usual accompaniments of white fly when death occurs.
As an illustration of the resisting powers of the orange to its
attacks, the Foster grove may be cited, the one before men-
tioned as being the first case of infestation on the West Coast.
This grove is referred to in some of the earliest literature of
white fly (Insect Life) and has been infested for more than ten
years; with the exception of a few trees, it is still living and
looks as if it can keep up the struggle indefinitely. When seen
by me about eighteen months ago the interior branches of most
of the trees had a color, thrift and vigor not found in some
groves wholly free from this insect. Except that the bearing
capacity of the grove has been reduced, it may still be called
one of the most valuable in the State. I was told by parties
acquainted with its recent history that it bears a good crop
about once in three years followed by two comparatively light
crops. It was hardly carrying more fruit than would pay for
the cost of maintenance at the time of my inspection of it.
Seedling groves are inclined to alternate heavy with light crops
so one of the light crops is accounted for, but the other is
doubtless due to the fly. I believe any practical grower will
think me well within the bounds of truth in saying that,
through a six-year period, the yield with white fly present
will be from twenty-five to forty per cent. less than it would
be with the insect absent. Manatee county alone produces
250,000 boxes of fruit per year and thirty per cent. increase
would be 75,000 boxes which, valued at $2.50 per box, would
amount to $187,500. This is not far from the actual loss, as
most of the groves in this county are infested. When the loss

616 BULLETIN NO. 67.

in other districts and the indirect losses due to impaired quality
and diminished carrying power are added, the State must
receive nearly a half million dollars less annually than she
would if the insects were absent. The acid and sugar content
of the fruit is much reduced, an orange from a white fly tree
being comparatively tasteless and insipid.
The following table shows the results of a chemical analy-
sis made at my. request by Profs. Miller and Blair of three lots
of fruit picked the same day from adjoining Dancy tangierine
groves, both of which were infested with white fly and had been
given practically the same treatment as regards cultivation and
fertilizing. Fifteen or twenty oranges were selected for each
of three lots, representing as accurately as possible the average
condition as to size and maturity on each of the three trees
from which they were taken.
Sample No. I was from a tree that had been infested for
several years and had been left to take care of itself.
Sample No. 2 was from a tree about forty feet from No.
I, and was regularly and properly sprayed three or four times
each year but stood in the row adjoining the unsprayed grove
and the insects could not be prevented from developing upon
it in numbers sufficient to cause more or less mold.
Sample No. 3 was from a tree about 80 feet from No. i,
which was properly sprayed as was No. 2, but with better
results. A few larvae were present on the leaves, but, practi-
cally, white fly could be considered wholly absent.

pPo' inr Niigar. Total Sugar Dextrose, Citric Acid,
i Per Cent. Per Cent.

Sample No. 1 2.18 6 71 .425
Sample No 2 2 23 6 26 .394
Sample No. 3 2 5S 7.91 445

These samples were collected in February after they had
passed their best, but it is believed that they kept their relative


A liberal use of fertilizer tends to keep up the quality but
the sooty mold upon the rind must be removed by hand-wash-
ing, by revolution in barrels filled with water and cross-cut
sawdust or by suitable machinery provided with revolving
brushes, and the consequent bruising of the rind invites quick
decay which often occurs in transit.
The subtraction of so much sap from the tree by the insects,
aided by the interference with assimilation caused by sooty
mold, delays ripening of the fruit, varieties which ought to be
at their prime by the first of December not being marketable
before Christmas time and often not until three or four weeks
The sooty mold is a black. saprophytic fungus, lcliola
Cainelliae (Call.) Sacc.. that grows in the honey dew excreted
by various insects. Among the Coccidae or scale insects which
it follows, may be mentioned the various Lecaniums, the mealy
bugs, the wax scales. Iccrya pilrchasi, and others. The plant
lice, or various species of Aphis, are also followed by ii as weil
as all forms of Alevrodidae which multiply excessively. Any
insect excreting honey dew in any quantity is certain to be
accompanied by the mold. Sooty trees and plants, therefore,
are not always infested by white fly, though such an appear-
ance upon any of the insect's food plants should receive an
immediate investigation. The white fly larvae being located
on the under sides of the leaves, the honey dew drops upon the
upper surface of the leaves growing just below, so the black
mold occurs chiefly upon the upper surface of the foliage and
fruit. It forms a close, smothering, membranous covering that
can sometimes be peeled back as if it were tissue paper. This
membrane is composed of the netted mycelial threads of the
fungus which reproduces by means of various reproductive
bodies some of which are shown in cut No. I, from Prof.
Hume's bulletin on Citrus Troubles. The wind is the chief agent
in disseminating the reproductive bodies. The effect which a
heavy coating of this fungus produces upon a tree differs only
in degree from what would be produced by enclosing it in a
black tent. The circulation of air through the tree and entrance

6i0 1 BULLETIN NO. 67.

of light is not interfered with, but contact of air and light with
the foliage is cut off on the upper surface and partially also
from the lower surface. The sooty mold is one of the most
aggravating factors of white fly damage. It disappears with
the destruction of the fly.

enlarged). I. Mycelium or fungal
with immature spores. (Drawing by

Natural Enemies.
The young of the lace-winged flies and a mite are the only
insects that I have observed feeding upon the eggs or larvae.
Lady-bugs possibly feed upon them to a slight degree but I have
never observed them doing so. A correspondent at Kissimmee


reports that a carnivorous ant is quite efficient as a destroyer
of the larvae. I cannot say that any of these appreciably reduce
the insect, even locally.
Through the kindness of Mr. Ehrhorn of California, some
hymenopterous parasites upon another species of Aleyrodes
were sent to me and enclosed on an infested tree beneath a
cheese-cloth tent. but several weeks later a freeze dropped all
the leaves from the tree and only a negative result could occur.
Further experiments of a similar nature are desirable, but too
much must not be hoped from them. The parasites of many
-other Alevrodidae in the State seem to have no taste for A.

Fungous Diseases.

If insect enemies are ineffective, the same cannot be said
of fungous diseases. Three species of fungi are known to find
their natural medium for growth in the white fly larvae, and
two of them are sometimes wonderfully successful, in certain
localities, in reducing the pest.
BROWN FUNG-us.-First in order of effectiveness must be
named the brown fungus whose botanical position is thus far
unknown and indeterminable because its fruiting has never
been observed. The fungus forms brown pustules of about the
size and resembling in some degree the red scale, Aspidiotus
ficus, differing from the scale, however, in always being on the
under sides of the leaves.
The fungus attacks all stages of larvae and pupae, the veg-
etative threads penetrating all parts of the body cavity, burst-
ing out as a fringe around the edges of the body, and then
growing up over it, forming a compressed hemispherical brown
wart or pimple (stroma), one over each larva destroyed. The
size of the stroma depends upon the size attained by the larva
when the fungus reaches it. From the base of the stroma
growing filaments or mycelial threads reach out sometimes to
the distance of half an inch in every direction. By such growth
other larvae are reached and thus the disease spreads rapidly

622 BULLETIN NO. 67.

over the surface of the infested leaf. Fragments of this myce-
lium are supposed to be transported by wind, birds or insects
to other leaves, trees and groves where they start a new infec-
tion. The fungus does little or no damage to the leaf, never
penetrating the tissues and only causing injury by smothering
under many of the breathing pores. The appearance of a well
matured case of brown fungus is well shown by the accompa-
nying photograph (Plate III, fig. 3.) taken by Prof. Hume.
THE RED ASCHERSONIA (Aschersonia aleyrodis Webber)
-This fungus is very conspicuous, forming more elevated pus-
tules than the brown fungus, and which are of a ruby-red or
pink color. The pustule, when matured, consists of a ruby-red
center surrounded by a fringe of pinkish orange, sometimes
approaching whitish. When immature the center consists of
several to many ruby-red cups developing in craters of pinkish
white. The red cups fill out, project slightly beyond their cra-
ters, and finally coalesce to form a ruby-red cone surrounded by
a light pink base-the matured form. The deep red material
consists of the sporules of the fungus and the lighter encircling
ring is its mycelial woof. The mycelial threads do not reach
out so far as those of the brown fungus and dissemination is
probably accomplished altogether by spores. The sporules are
gelatinous and adhere together so strongly in masses that the
wind would seem unable to scatter them. The spores are loos-
ened by the masses becoming wet, and heavy dews or light
showers combined with a fluttering breeze so that drops of
water are shaken from one leaf to another is probably one
means of scattering them. If all the pustules were exposed to
the full force of a heavy, driving rain, all the sporules would
probably be dislodged and carried to the ground, but it is con-
jectured that their position on the under surfaces of the leaves
protects them from too rapid dispersion under such circum-
stances, and at the same time gives possible opportunity for
spreading them. The young larvae move about freely for
several hours upon the leaves on which they have hatched and
occasionally pass to other leaves, and while thus traveling can
become infected with the disease before settling permanently;


however, it is safe to say that the insects that become infected
in this manner are exceedingly few.
Ants are possibly important agents in distributing the
spores. They visit the leaves for the purpose of feeding on
the honey dew excreted by the white fly larvae and they could
hardly pass over thoroughly infected leaves without entangling
spores in their feet, especially if they were sticky with honey
dew, and such spores would be readily transferred to the next
larva visited. The first indication of larval infection is the
appearance of translucent yellowish spots, usually near the
edge of the larva, which becomes swollen and instead of throw-
ing off its honey dew to the leaves beneath it, as is customary,
allows it to accumulate over and around its body. The honey
dew, being an excretory product, this early manifestation of the
disease may be characterized as a violent diarrhoea. The
hyphae or threads of the disease occupy a circle around the
margin of the body, through which they eventually burst as
a surrounding fringe. Death usually occurs before the hyphae
appear through the ruptured margin. The threads, instead of
reaching out over the leaf surface to any extent, grow into the
larval body and over it, finally hiding it completely and forming
the matured pustule as before described.
known as a parasite on scale insects, has been received from
Orlando, growing upon A. citri. So far as can be judged at
present its work upon white fly is comparatively insignificant,
but under favorable conditions it might become a factor of
considerable importance. The fungus appears, when matured,
as stumpy, elongated, coral-reddish tufts around the body
margin and on the dorsal surface, but rarely or never conceal-
ing the insect. The biology of this fungus is discussed by Prof.
P. H. Rolfs in bulletin No. 41, of this Station.
BLACK FUNGUS OR SOOTY I\IOLD.-I have received the
sooty mold covering the under surfaces of the leaves and
smothering many of the larvae, with the report that it was "a
fungus destroying the fly." In some instances I have seen 40
per cent. to 50 per cent. of the larvae smothered to death by it; it


has no effect in killing the insect until infestation is excessive,
and ceases to operate as a destroying agent when the larvae
are sufficiently reduced in number to stop the flow of honey
dew over the lower surface of the leaf.

Methods of Introducing these Fungous Diseases into Infested

Until more is known of the developmental history of these
diseases it will be wisest to approximate the conditions under
which Nature spreads them as the surest way of getting them
established where they do not at present exist. Introduction
can, perhaps, be most satisfactorily accomplished by planting in
the infested groves trees upon which the fungi are well estab-
lished. The trees should be planted so that twigs of the infested
ones interblend with those having upon them the diseased
larvae in order that the leaves of the two may thus be brought
into contact. If the transplanted tree is small it may be
planted in a tub and elevated to the proper height on a box, or
the tub may be fastened in the fork of the tree which it is
desired to infect. Even this method sometimes fails but it com-
monly succeeds. The time of transplanting is not important,
the essential point being to get the tree to growing without
dropping its leaves.
Pinning of fungous infested leaves with the fungous pus-
tules in contact with the healthy larvae of uninfected leaves
and thus leaving them; spraying with spores of the fungus
and fragments of its mycelium suspended in water; hanging
of cut infected branches among uninfected ones; inoculation by
means of lightly pricking the larvae with a needle which has
just been immersed in water containing an abundance of spores
and fragments of mycelium; and placing the infected face of a
leaf in contact with the larvae on an uninfected one and
securing them in this position by means of a cheese-cloth band
which binds in a moistened plaster of cotton or moss on each
side of the leaf, have been tried by various experimenters, my-
self included, without marked success. However, an infection

Fig. I.

Fig. 2.

-OMKIWM MI Fig. 4.
Fig. 3.

Fig. I.-Larvae and pupae of White Fly on Orange.
Fig. 2.-Red Fungus, Aschersonia aleyrodis Webber.
Fig. 3.-Brown Fungus on Orange.
Fig. 4.-Adult Flies and Eggs on Orange.


. . m -3 ,


is sometimes started by these methods. When the last is used
the cotton or moss is moistened by pouring water upon it every
two or three days and the bandages are removed in a week
or ten days; care must be taken not to make the bandage so
heavy that it will break off the leaf when the cotton is saturated
with moisture.
How Far May the Fungus be Trusted to Destroy the Fly?
Different observers will give different answers to
this question. Some intelligent growers, located near the coast
in South Florida where conditions of heat and moisture are
as favorable as they possibly can be for fungus growth and
development, are sanguine in the belief that no spraying is
necessary, while some of their neighbors are equally confident
that the highest degree of profitable production can only be
reached by diligent spraying or fumigation. Classed with
neither the sprayers nor the non-sprayers is a numerous contin-
gent that is confused between the claims and practices of the
two schools, and therefore its representatives spray a
little, then wait a year or two for the fungus to
develop, then spray a little more, then wait again for
the fungus to appear. This mixing of the practices
of the two schools fails to secure the benefits of either and
groves that are improperly, intermittently or rarely sprayed
would best be left wholly untouched if any fungus is present
in them. I once thought there might be a middle road of
practice between the two schools and that by observation of the
natural agencies at work to destroy the insects it could be
decided whether spraying was or was not necessary. While
this may be true under some circumstances, careful observation
for four years has convinced me that for the orange grower
in Florida the truth lies at the two extremes of practice and not
at all between them. I cannot too emphatically state my con-
viction that if one in this State is to trust his natural friends to
destroy his insect enemies, he must carefully study the habits of
these friends, introduce them, propagate them, disseminate
them, and allow them to spread and multiply without hindrance
by the application of caustic sprays which destroy friend and


foe alike. Fungi are easily destroyed by alkaline washes and
soaps, whether the alkaline base is caustic potash, caustic soda,
or lime; and in Florida with its long, hot, humid summers
fungous diseases are commonly many times more effective than
predaceous or parasitic insects. Where fumigation is practica-
ble it has one distinct advantage over spraying in that it does
not destroy fungous growths. The man who is not willing to
leave the safe-keeping of his grove in Nature's hands should
plan to spray regularly several times each year and the expendi-
ture should be counted upon as an outlay just as necessary as is
his fertilizer bill. I believe that seventy-five per cent. of the
groves in this State, whether infested with white fly or not, if
handled in this way, would show an improvement as marked as
a properly fertilized grove shows over an unfertilized or an
improperly fertilized one. I repeat emphatically that while
I have no word of condemnation for the man who with intelli-
gence and skill directs Nature's agencies so that he secures
results with most insects equal to the best (and we have some
such in Florida), I believe that white fly is an insect that
should be fought by everybody with insecticides from the dav
it is discovered in a grove. I admit that there is no spray
that will kill white fly and not at the same time inflict injury to
the trees upon which it is so often applied, but I am satisfied
that the injury is far less than white fly causes, except during
exceptional periods when fungous diseases are unusually active.
Infested trees that are properly sprayed through many years
and are correctly treated in other respects, I believe will live
longer, yield better, and give much larger net profits than they
will do if fungi alone are relied upon for protection.
The views of Mr. A. J. Pettigrew, being based upon many
years of observation and the trial both of spraying and depend-
ing upon fungi, I think too valuable to omit. Mr. Pettigrew
regularly sprays such of his groves as are planted on pine land
in open fashion, that is where the distances between the trees
are great enough to admit of the free circulation of air among
them; but in case of close-planted trees on hammock soil and


especially when still closely surrounded by hammock woods, he
depends wholly upon fungi.
Many of the attempts to introduce the fungi into the upper
parts of the State have failed, and I have never seen the diseases
doing effective work very far from the coast. In old orange
days Prof. Webber records having seen the red Aschersonia in
abundance at Gainesville and Panasoffkee. At present the dis-
tricts in which the two important diseases are really successful
are along the Manatee river and about Fort Myers. It is impos-
sible to accurately judge at present what these fungi will do in
the upper and interior parts of the State.
For practice, I recommend that one having an infested
grove either spray it or fumigate it according to circumstances;
that he persuade his neighbors to do likewise if possible: if the
neighbors are obdurate and will not treat their trees, persuade
them to introduce the fungi as the next best thing; if they will
not do this it may be worth while to introduce the diseases for
them and then work to create a State Entomological Depart-
ment with sufficient resources at its command to enable it to
supervise the introduction of such valuable fungi into every
neglected and infested grove in the State.
Mr. A. J. Pettigrew, Manatee, Fla., has kindly given per-
mission to refer to him as being prepared to supply for the
trade, trees having upon the leaves both the red and the brown
fungus in suitable condition for introduction into new localities.
The frank honesty, which through many years has character-
ized Mr. Pettigrew's dealings with the public and which now,
in the interest of the public welfare, induces him to allow the use
of his name in a way that most nurserymen would shum.
deserves the appreciative consideration of our people. If some
citizen had not consented to do what Mr. Pettigrew has done
I know of no regular source of supply of these diseases that
could have been named, and I am not provided with the
resources by which the work could be undertaken by my depart-
ment. I feel sure that no one need fear to order defoliated,
clean stock of Mr. Pettigrew, for his past record and present
attitude is a certain guaranty that it will be furnished.

Bul. 67-3



As before noted three of the four pairs of spiracles or
breathing pores of the larva are on the under surface of a V-
shaped fold or groove,with the apex directed backward,which is
readily observed at the anterior end of the body, approximating
the separating line between tie lead and thorax; and indeed
this fold was once supposed by entomologists to be the dividing
line between head and thorax; but as observed by Prof. Wood-
worth, it is wholly thoracic-in position and is a specialized appa-
ratus for respiration.* Another or fourth pair of spiracles is
on the under surface of an anal groove or fold. Since the larva
is very closely pressed against the leaf and the only ingress of
air to the spiracles is through the grooves or breathing f(ods
mentioned, the efficacy of the resin sprays which close up the
outside apertures of the breathing folds is readily understood.
It is only necessary to obtain a ring of resinous wax around
the body-ring of the larva, thus forming an hermetical seal, to
suffocate it. If one or more of the four tube openings are left
unstopped while the others are closed the insect will probably
survive just as a man with one lung will survive for a time; and
if a rain comes to uncover the stopped tubes within ten or
fifteen days, it will probably recover altogether, whereas, if
all the tubes are closed it will die in a few hours. The structure
of the insect would seem to indicate that a fine and evenly
distributed spray would be most effective; but resin wash,
going through a fine nozzle, froths a good deal, including so
many air bubbles that a certain degree of coarseness of spray
gives best satisfaction. A caustic property in the spray is
also important in order that death may result before rains dis-
solve off the wash.
The formula in general use and which is most satisfactory,
for regular work, cost and efficiency considered, is the one orig-
inally recommended by Prof. Webber, and is as follows:

*Canadian Entomologist, Vol. 23, June I90o, p. 173.


I Resin, pulverized ... ......... .... ..2 lbs.
Caustic Soda. granulated, 98 per cent .... 4 I-4 bs.
Fish O il...... ............ .. .. ......3 pts.
W after for final bulk ........ .... .... 15o gals.
A somewhat cheaper formula is the following:
2 Resin, pulverized. ........... .. ..... .2o0 bs.
Crude Caustic Soda, 78 per cent...... ..... 4 lbs.
Fish Oil .................. .... ..2 1-2 pts.
Water for final bulk ........ ioo gals. to 50o gals.
Ordinary commercial resin, such as is bought by the barrel
in Florida, is satisfactory, and the caustic soda is of the quality
used in soap factories. The crude soda comes in drums of
from 112 to'200 pounds each.
Another formula which has given good satisfaction to
some growers because of the convenience of quickly obtaining
the materials without ordering them from a distance and of
keeping the suda indefinitely without special precautions is as
3 Resin. pulverized ...... ...... ......... 20 lbs.
Caustic Soda ( Star Ball Potash, pulverized) 7 Ibs.
Fish Oil ...................... ... 3 1-2 pts.
W ater for final bulk. ............... .. oo gals.
Resin costs I 1-4 cents per pound. or if obtained direct
from the naval stores farms I cent per pound or less. Caustic
soda is quoted in Jacksonville at 8 cents per pound in ten-pound
cans. 7 1-2 cents per pound in 25-pound cans, 7 cents per pound
in 5o-pound cans. This substance rapidly absorbs water from
the air, becoming a very caustic liquid and is therefore best
purchased in packages, the entire contents of which can be used
at once after opening. If small quantities of spray are needed
the smaller packages should be purchased. The crude caustic
soda costs from 3 i-2 to 4 cents per pound in New York,
f. o. b., and cannot be obtained in small packages. It becomes
of an adamantine hardness after being exposed to the air for
a few days and should be worked up at once after opening the
drum. It is suitable for use where the grove is large and the

ti~ BULLETIN NO. 67.

spraying outfit, from preparing plant to number of nozzles at
work, is of considerable magnitude. Star Ball Potash comes
in cases of 48 pounds each, one-pound balls, at $3 per case or
6 1-4 cents per pound. It may be exposed to the air for any
length of time without being injured as each ball is covered with
a resinous jacket. It can be obtained from almost any large
grocery. Fish oil costs about 50 cents per gallon. The mate-
rials for Ioo gallons of spray made by formula I will cost
about 51 cents, by formula 2 about 6o cents, and by formula
3 about 90 cents. Formula I diluted to the same degree as the
other two will cost about 76 cents per one hundred gallons.
As a smothering wash formula i is probably equal to 2
and 3, but its contact effects are less satisfactory. If the wash
is to be used in summer the dilution is about right, but for
winter use better results are secured by diluting to Ioo gallons
instead of I5o. The materials for resin wash can be had from
almost any wholesale dealer. Among the best known firms
in Florida may be named E. O. Painter & Co., Wilson &
Toomer, and C. R. Tysen, all located at Jacksonville.
The details of preparation are the same no matter which
formula is used. Procure a large iron kettle, a hog scalding
vat is excellent, and another smaller kettle for hot water. If
a large kettle of from twenty-five to forty gallons capacity is
unavailable, a number of smaller ones can be used, the materials
being divided between them as they are weighed out and
measured. Heat in the large kettle thirteen or fourteen gallons
of water, having previously placed the materials given in one
of the formulae in the bottom. If the water is hot before the
materials are put in, add the resin and fish oil first and then the
soda in small lots to prevent a sudden boiling over. Boiling
is best continued for two or three hours over a hot but not too
brisk fire. One hour's boiling or less will give a mixture which
can be used but results will not be as satisfactory as when the
wash is more thoroughly cooked. Whenever there is a ten-
dency for the liquid to boil over, subsidence will quickly occur
if a pint or more of water from the water kettle, which is kept
warm but not boiling, is added. Never add cold water while


the wash is cooking if you desire results that are certain.
Increase the quantity of solution by gradual additions of warm
water until a stock solution of thirty gallons is obtained. For
use, this is to be diluted to one hundred-fifty gallons in case
of formula I, to one hundred gallons with formula 2, and
one hundred gallons with formula 3. The stock solution may
be kept for a time and used as desired, but the wash is best used
as fast as made. Any sediment or settling in the stock solution
indicates that cooking was incomplete and must be repeated.
Where a steam pump is possessed or a head of steam is availa-
ble a set of barrels may be arranged with steam pipes leading
through them and resin wash can be prepared rapidly and in
quantity by boiling with steam. The stock solution should be
strained before diluting it to remove any particles or trash that
would clog the pump nnzzle.

Other Sprays and Remedies than Resin Wash.

KEROSENE EMULSION.-Kerosene used as an emulsion or in
a ten per cent mechanical mixture with a kerowater pump is an
efficient destroyer of the larvae and eggs of the fly, but is some-
what uncertain in its effects upon the tree. The emulsion,
properly made. is much more reliable than the mechanical appli-
cation, made with a kerowater pump. Bright, sunny days with
a dry atmosphere should be chosen for making kerosene appli-
cations. If applied upon a cloudy, humid day that is followed
by several days of cloudy weather, thus interfering with rapid
evaporation of the oil, very serious injury to the trees is apt to
follow. From ninety to ninety-five per cent of the larvae are
killed by one thorough application. An occasional spraying
with the emulsion may not he objectionable, but I do not recom-
mend it for continuous use. Crude pretroleum should never be
used upon citrus trees.
W1IIALE OIL SOAP.-Any good whale oil soap will be found
useful in fighting white fly. Of the hard, or soda soaps, Leg-
gett's Anchor Soap is probably not surpassed. The true potash
soaps seem to give better results with the insects and trees, con-

632 BULLETIN NO. 67.

sidered together, than any of the insecticidal washes, when used
continually for several seasons, as must be done in case of white
fly. Good's Potash Whale Oil Soap No. 3 is well suited for such
use and is safe as a summer application. Used at the rate of
one pound to four gallons of water it will kill about sixty per
cent of the grown larvae in March, and, when used at the rate
of one pound to three gallons of water on half grown larvae
in May or early June, from eighty-five to ninety-five per cent
of them are killed. Though a very heavy rain fell within two
hours after making an application at the latter strength in early
June, not less than ninety per cent of the insects were dead two
or three days afterwards. Leaves, having upon them pupae
from which the adults were emerging and larvae in less ad-
vanced stages, when immersed for ten minutes in a solution of
the soap, one pound to four gallons of water, have invariably
had all the insects upon them killed unless they were peculi-
arly sheltered.
In laboratory experiments, Good's Tobacco Whale Oil Soap
No. 6 did not seem more effective than did the No. 3 soap, but
in the field one pound of it in five gallons of water seemed to
give somewhat better results than one pound of the No. 3 soap
in three gallons of water. Leggett's Whale Oil Soap Compound
a true potash soap, used at the rate of one pound in three gal-
lons of water, gave, in the field, about the same results as
Good's No. 3, but in laboratory tests it seemed to be not so
For summer use and for trees that have been weakened
by the use of more severe sprays, the potash soaps are especially
Purchased by the half-barrel, Good's Potash Soap No. 3
costs 3 1-2 cents per pound; or, if used at the rate of one pound
in three gallons of water, one hundred gallons of spray will
cost $1.17; if the dilution be one pound to four gallons of
water, one hundred gallons of spray will cost .87 I-2 cents.
HAMMOND'S THRIP JUICE.-This preparation made by
Benj. Hammond. Fish-kill-on-the-Hudson, N. Y., is apparent-
ly a very concentrated potash-tar soap which readily dissolves


in warm water. In twenty gallon kegs, it costs $1.60 per gal-
lon, and as the dilution recommended is one part of Thrip
Juice to one thousand parts of water, one hundred gallons of
spray will cost sixteen cents. Used at the dilution given re-
sults have not been satisfactory at all as compared with those
gotten with the use of potash whale oil soaps applied at the
same time and under the same conditions. A few of the young-
er larvae were killed, but nearly all of the well-grown ones sur-
vived. It is possible that this insecticide, diluted about one
part of Thrip Juice to eight hundred parts of water, will prove
a valuable application to use about the middle of May or a little
earlier when the larvae are all quite young.
MONTGOMERY'S INxECTICIDE-Apparently a potash-soda-
tar-resin preparation, with possibly other unknown ingredients,
the whole quite resembling the ordinary resin wash. Since
part, and possibly the largest part, of its base is true potash.
the wash is apt to be more stable than the ordinary soda wash
and is therefore probably better suited for summer use than
many preparations. The full effect of the wash is not apparent
until several days have passed after spraying, but so far as
tested, results have been quite as satisfactory as with any prep-
aration used. The stock preparation is sold by Dr. L. Mont-
gomery and Son. Micanopy, Fla., at $8.75 per barrel of 5o gal-
lons. For use, the stock preparation is diluted one part to
seven or ten parts of water: one hundred gallons of spray,
therefore, cost $2.50 at the former dilution and $1.75 at the
ToBAcco DECOCTION.-Tobacco infusions at all strengths
are practically worthless, the effect on white fly larvae being
little more marked than if rain water were used. The larvae
may be immersed in such decoctions for several hours without
being killed. Roseleaf Insecticide, a patented preparation of
tobacco extract, gives results but little better than the ordinary
SULPHUR DusT.-Dusting the trees liberally with flowers
of sulphur when the young are hatching has been found to be
of no value at all.


CAMPHOR BALLS.-Camphor balls enclosed in cheese cloth
sacks and tied in the trees as repellants are worthless.
LIGHT TRAPs.-Trapping the adults with lights gives no
results worth mentioning.
FIGHTING THE ADULTS.-Varfare of any sort directed
against the adults is doomed to failure, since the females gen-
erally lay their eggs within twenty to forty-eight hours after

When to Spray and What to Use.
Spraying must be so timed that the greatest number of
insects are destroyed, and another and even more important
consideration is to avoid injury to the tree, bloom and fruit.
Spraying cannot be done effectively while the insect is on the
wing. There are three larval periods, the longest of which
extends from late November until the first of March; another
extends through May and June; another without well defined
limits through late July, August, September and October. The
winter larval period offers the best opportunity for satisfactory
spraying. Two thorough applications of resin wash should be
made during this period as a regular practice and, if a grove is
badly infested, the first year that spraying is adopted three
may be made with profit. The earlier the spraying is done the
less will be the sapping of the trees by the larvae during the
winter. The first spraying should be done in December, if
possible, and the second in January. A third may be made in
Spraying should cease when the blossoms commence open-
ing, but may be continued until the buds are swollen and ready
to burst. A swollen bud in spring is not more liable to damage
from a resin spray than it is during the winter. No spraying
with resin wash should be done during- April, May or early
June. Some growers have dropped many thousands of dollars
worth of fruit by spraying in late May in South H lo' da, and as
it has been the experience of not a single grower but of a num-
ber and of not a single season but of several, the conclusion must


be stated with emphasis thatspraying bearing trees with resin
wash during the spring larval period is hazardous. Late May
in South Florida corresponds to early June in the northern
orange section. Spraying with resin wash at any time during
June is questionable.
So far as present experience and reports indicate a potash
halee oil soap may be used with safety after the fruit has been
set for two or three weeks. Where the flies are bad a soap
spray may be used in late May or early June. This will dimin-
ish the June and July hatching of adults and therefore tend to
hold down the numbers of the second brood of larvae which
cause the smutting of the fruit. Either the resin wash or soap
can be used in July, August and September without danger of
dropping fruit, but some scarring and burning will be caused by
the former. For summer use I am inclined to believe that a pot-
ash soap, used exclusively, will give best results. If a quart by
measure of flowers of sulphur is dissolved by boiling with ten
pounds of soap in twelve or fifteen gallons of water, the solution
being diluted to thirty or forty gallons of liquid for use, a spray
is obtained that is effective against the purple and six-spotted
mites, the rust mite, scale insects and white fly. Three or four
well made applications during the summer, about a month
apart and timed to catch the white fly larvae, will keep the fruit
free from rust, scale and sooty mold if winter treatment was
properly made.

How to Spray.

A good force pump, capable of supplying two to four
nozzles and of elevating the spray when required to a height
of thirty-five or forty feet is a necessity. Among the hand
pumps that can be recommended as filling such requirements
may be named the "Friend" pump made by the "Friend" Manu-
facturing Co., Gasport, N. Y., and the Gould Sentinel Junior
pump made by the Gould Manufacturing Co., Seneca Falls,N.
Y. There are other good pumps than these, but as I have had
practical experience with both of these machines as well as


others I can pronounce them among the best. The latter is well
known to our growers. The former is yet a stranger to them,
but is something unusually good and deserves an introduction
for high power work. If steam, gasoline engines or com-
pressed air pumps-capable of supplying from six to twelve
nozzles-are wanted, correspond with such firms as these:
Gould Manufacturing Co., Seneca Falls, N. Y.; Friend Manu-

The "Friend" Pump. Gould's Sentinel Jr. Pump.

facturing Co., Gasport, N. Y.; Wm. Stahl, Quincy, Ill.; Dem-
ing Co., Salem, O.; The Pierce-Loop Sprayer Co., Northeast,
Pa., or Field Force Pump Co., Lockport, N. Y.
The leads of hose should be long enough to carry the
extension rods, well towards the tops of the trees. Ladders are
sometimes used in reaching the tops of very tall trees. A high


platform is sometimes erected on the spray wagon above the
tank on which the operators stand to reach high tops, but as
spraying for white fly must be from the inside of the tree out-
ward instead of from the outside inward, such a platform is
of little use unless the wagon is driven very close to the tree.
Brass extension rods encased in bamboo are less unwieldy than
the ordinary gas pipe extension rods and should be eight or ten
feet long.
Nozzles that can be adjusted to throw either coarse or fine
spray are to be preferred for applying resin wash or whale oil
soap, and the spray should be put on as fine as it can be and at
the same time carry well to the foliage. Resin wash when too
fine behaves like fine soap bubbles, drifting in the air instead
of going to the point at which the nozzle is directed. Nozzles
of such types as the Nixon, Bordeaux, McGowen, Seneca,
Masson, etc., are suited to this work. For applying any of the
preparations of kerosene a fine Vermorel nozzle should be used.
A nozzle than can be adjusted to any angle so as to reach
the under side of the leaves from any position, such as the
Gould's Carnation or Erin, is at times a convenience but is not
so necessary as it may appear to be to one who has not learned
that the underside of nearly every leaf upon a tree, as ordinarily
grown, can be covered by using a straight rod nozzle. The
underside of every leaf must be hit and well covered with spray
to kill the white flv larvae. The operator must not be afraid of
the drip and should stand well under the tree and thrust his rod
through the forks so the spray will be thrown with good force
against the lower leaf surfaces. For high trees having thick
foliage a powerful pump is necessary to drive the spray through
to the top.
Some growers prune out all the interior growth from their
trees so as to leave them hollow cones. Such trees are easily
sprayed, but other growers believe the resulting gain is more
than offset by losses in other directions. An excessive growth
of water sprouts is often stimulated by too severe pruning, and
these are specially attractive to the flies. A growth of water
sprouts is the normal outcome of an effort by the tree to remedy


an abnormal condition-that is, to balance a sufficient top
growth against a root system that is overdeveloped. Insuffi-
-cient drainage is a cause sometimes inducing excessive root
growth, and hence indirectly influencing the development of
water sprouts. Cutting all of them out, along with the interior
fruit twigs, encourages a new and more numerous growth of
them. Where it is possible to do it train them to grow outward
in the foliage zone and allow them to harden and become
ordinary normal wood as soon as they will. When they are
in the heart of the tree and numerous it is necessary to cut them
out as well as dead twigs before spraying is commenced.
Trees upon tall trunks are readily developed into the
hollow cone. I believe the foliage zone of such trees should
be deep, and if spraying seems difficult effort should be directed
toward obtaining a pump of higher power rather than to dimin-
ish the depth of the foliage by pruning. If low branched,
squatty trees are more difficult to spray, they are much easier
to fumigate than high-topped ones, but can also be sprayed
With low trees an adjustable or elbowed nozzle for throw-
ing the spray upward is almost a necessity. The operator will
often find it best to thrust his rod through to the side of the
tree opposite from where he is standing, thus hitting
the under surfaces of the leaves on that side. With low-topped
trees having dense foliage most of the work must be done by
this method. Some of the leaves, especially at the top, are
best reached from a position outside and away from the tree.
A clever operator will quickly learn by experience how most
conveniently to send the spray where it is needed. The quan-
tity of spray used should be liberal. One thorough spraying
is cheaper than two that are half done. Trees from 12 to 20
feet high will require from 8 to 15 gallons of spray; from 20
to 30 feet high from 15 to 25 or 30 gallons of spray. Use more
than these quantities rather than less.
The following extracts are taken from letters bearing vari-
ous dates, written by well known orange growers whose large


experience with resin and soap washes gives deserved weight
to their opinions:
"I have used resin wash against white fly for eleven years
with perfect success. My long experience with its use has made
me very familiar with its effects on trees and fruit at whatever
season of the year applied. Several years ago I lost many mhn-
dreds of boxes of fruit by using it in May. I used it again last
May, the weather conditions being identical with what they
were when I previously lost fruit, namely, very hot aid dry.
I think the resin draws the heat and scalds the oranges. An
experiment in which I diluted Professor Webber's stock solu-
tion of wash to i80 gallons instead of 150 gave tihe same results.
We Yost last May I,ooo boxes of oranges worth from $2,500
to $3,ooo had they matured. William Palmer, Sam Harris
and L. C. Randall all used the wash at the same time with ihe
same results. I am positive that the wash will take the fruit
off every time in theiMay period.
"I have kept the white fly under control ever since I com-
menced spraying. The only tree that ever became black with
smut were near neighboring groves that were never sprayed at
all,or else not thoroughly. The fly has not yet reached some parts
of my grove. (Mr. Kirkhuff's grove contains about 2,300
trees.) I have sometimes thought the resin spray has some
effect in hardening the bark. I thoroughly soak the entire tree.
I find, when so applied twice, it takes off about one-third of the
foliage and causes ripe fruit to drop badly. I have sprayed
in August and September when the weather was dry and had
good results in keeping down the sooty mold on tree and fruit.
Nearly all the larvae were killed.
"I commenced by spraying once in January, once in May
and once in August. After discovering the danger of spraying
in May I gave one application in winter, one in August and
another in September. I now spray in winter making two very
thorough applications. I believe that I do not have fifty trees
out of 2,300 that have any smut on them. I may be obliged to
wash a few boxes of oranges."-W. I. Kirkhuff, Braidentown,


"I was well pleased with the results of spraying for white
fly last season. My tangierine grove was comparatively free
from fly, so much so that I shipped all the fruit without washing
any of it and it was 90 per cent.'fancy bright.' Only about 200
boxes out of 3,500 from the Bank of Kingwood Grove were
touched by the fly and these not badly. By being careful to
keep all the water sprouts from the trees and spraying well
(with resin, fish oil and Star Ball Potash) once or twice in
January or February we have kept the fly out of our groves for
the past two years. Mr. Nichols was well enough pleased with
his last year's spraying to spray again this year.
"I have never sprayed with resin wash in the spring,
June being the earliest date I have tried. I have never had any
fruit to fall from the use of the wash, but have had a small per-
centage of the fruit to burn where it was most exposed to the
sun-perhaps from 2 to 5 per cent. of it; from the entire
grove, 2 per cent. would probably cover the amount of burnt
fruit."-C. P. Fuller, Ellenton, Fla.
"I beg to say that after making experiments with varying
strengths of the Good soap, I have found 18 pounds to 50
gallons of water just right. I would not hesitate to spray at
any time with this soap, and have actually sprayed the bloom
to kill thrips, apparently without injuring the crop of fruit.
It is a safe preparation to use, and I have found it will rid the
trees of scale, and I feel sure it will be effective against the
white fly.
"I have long contended against the use of resin wash and
have had, in the past, bad results on young fruit from its use."-
E. P. Porcher, Cocoa, Fla.
"I have no very definite idea as to the effect of spraying
very young fruit with Good's whale oil soap, as I have always
avoided spraying trees when fruit was passing through the
dropping stage. By the time that the fruit is the size of mar-
bles most of the weak ones have dropped off, and from this time
on I have used Good's potash soap without seeing any bad
results from it, but I have burned spots on oranges two-thirds
grown with soap of my own make when used at a strength


of one pound to four gallons of water-; but this soap was much
stronger than Good's, having less than one-half of the water in
it that Good's has.
"I have never noticed any direct injury to trees from one
application of resin wash, but when applied as often as three
times inside of three or four months it certainly does injure
a tree to such an extent that it will take an entire season for
it to recover."-C. W. Butler, St. Petersburg, Fla.
Mr. Porcher and Mr. Butler have not had experience in
spraying for white fly, but their knowledge of the comparative
effects of the resin washes and potash soaps upon trees and fruit
can be depended upon as valuable.

Scalding Action of Resin Wash Explained.

Sodium resinate, formed by boiling together sodium
hydroxide and resin, is a salt composed of a strong base and a
weak acid; in the presence of moisture it easily separates again
into sodium hydroxide and the original acid. Chemical sepa-
ration is especially apt to occur if cooking the wash was incom-
plete or hurried. The following, therefore, is the probable
explanation for the scalding and falling of the fruit:
The hermetical seal or covering of resin on the young
fruit prevents evaporation, thus confining, within, the moisture
necessary to cause the dissociation of the chemical elements con-
stituting the inside of the resin jacket; and these being held
by the outside layer of resin in contact with the young and
tender fruit pulp for an indefinite time cause scalding and burn-
ing, culminating in the dropping of the oranges. It is also pos-
sible that there is some accumulation of heat inside the resin
shell. Anyone who has worn a pair of rubber boots for a
short time in the sunshine on a hot summer day knows that his
feet scald. The explanation is found in the fact that evapora-
tion is prevented, and rubber also possessing a great capacity
for absorbing heat, an accumulation of it occurs inside the boot.,
By a somewhat different principle glass enclosures accumulate


heat within,the phenomenon of plants burning in a closed green-
house in hot sunshine being a familiar one. According to the
results obtained by Mr. W. W. Coblentz of Cornell University,
resin is not highly diathermous like glass, but possesses
a moderate transmitting power for heat. I think it not improb-
able that the accumulation of heat inside the resin shell is suffi-
cient to stimulate the chemical activities which, but for its
presence, would inflict less injurious effects. As the fruit
increases in size it becomes of tougher character and, rela-
tively, so small a portion of the pulp is burned that scalding
occurs only in spots, not involving enough of the flesh to cause
falling. It is also conceivable that, to a smaller extent, drops of
the wash accumulating on the undersides of the fruit, harden
into more or less persistent concavo-convex lenses, with suffi-
cient curvature to focus such of the sun's rays as strike them
to centers inside the shell, thus furnishing an excess of heat
in a local spot, possibly not enough ii itself to cause burning
but sufficient to encourage unusual chemical activity in any
free sodium hydroxide near such a point. No matter which is
the primary agent in causing the falling, whether chemical or
physical, it is associated with hot, dry weather and direct sun-
shine, heat being an important factor in causing it. Besides
the original accumulation of wash in drops on the lower part of
the fruit, the dews and light rains will regularly carry more of
it to the same spot and at the same time stimulate chemical
disintegration, thus subjecting such spots to the action of
sodium hydroxide for a continuous and indefinite period. In
like manner some of the fruit may be so located that the
drip from dew or light rain from above falls constantly on the
same spot, causing a scalded place on the upper surface or side.
The relatively large calyx cup receives and holds consider-
able quantities of the spray and this in breaking up into sodium
hydroxide and resinous acid would scald the tender stem of the
fruit, inducing shriveling and falling. It is probable that most
of the dropping is caused by injury to the stem.



Fumigation with hydrocyanic acid gas is recognized in
nearly every progressive citrus producing country in the world
as one of the most effective methods for destroying orange
pests. A process that has been found so valuable in every other
part of the world is certain to eventually come into favor in
Florida. The conditions that exist in our State set some limita-
tions upon its range of usefulness and I think it should not
be "boomed" into disfavor. but a gradually increasing number
of growers can adopt it each year with profit. The Florida
growers have had little experience in fumigating trees and
think the method intricate and mysterious. Familiarity with
such work removes such misconceptions and it is discovered
that a fumigation outfit is not more mysterious or difficult of
mastery to an orange grower than is a spray pump with its
accompaniments to a grocer. It is well-nigh necessary, how-
ever, to secure the help of an experienced fumigator when
beginning such work.
Since it will be necessary. at a later time, to publish direc-
tions for fumigating in the field I will burden as little as possi-
ble the already full pages of this bulletin with the details of such
work, giving only a resume of the results reached two years
ago while working in conjunction with Prof. C. WV. Woodworth
of the California Experiment Station. Upon Prof. Wood-
worth's arrival in Florida. our first work was to visit the Mc-
Farland Tent Factory, then located at Titusvilie, and look to
the selection and treatment of cloth, patterns of tents, etc.
Six ounce drilling, treated with paraffine, a sort of cloth used
by the company in the manufacture of tents for protection
against cold, was tested, but seemed to allow too much escape
of gas. Several patterns of tent, sheet, hoop and bell were
made ready, using either eight ounce duck or six ounce drilling,
some of our largest bell tents for trees thirty feet in height and
twenty-five feet in diameter being made from the latter material.
In practice, the drilling proved quite satisfactory for the smaller
tents, but was too easily torn for heavy work. Subsequently,

644 BULLETIN NO. 67.

the people of Candler, Florida, have used a light, six-cent
muslin quite satisfactorily, but I am inclined to recommend
heavier cloth. The cloth for the Station tents was mildew-
proofed at the factory. and when on the ground where-it was
to be used, was painted with linseed oil, into which enough
lamp-black was stirred to give body and color to the prepara-
tion. We experienced some trouble with burning of cloth; in
fact, found it impossible to paint a large bell tent without
serious damage, necessitating extensive patching, unless the
derrick upon which it was swung was in perfect working order
and repair, so as to avoid the risk of leaving a fold in the canvas
for even a short time while drying out. The weight of oiled
tents is also a great objection to them. Cactus juice. which is
sometimes used in California, is not available in Florida in suffi-
cient quantities for tent treatment and some new application
must be found. Fortunately a preparation, known to sailors
in tropical waters has come to my attention and, except that it
renders cloth somewhat objectionable for handling, has thus far
given good satisfaction. Mr. Arthur Weaver, who superin-
tended the fumigating of Mr. A. G. Liles' grove, used the prep-
aration and reported it lighter, cheaper, and in all respects supe-
rior to oil with which he had had equal experience. It senms
not to burn cloth and to be mildew-proof. Cloth so treated and
in use upon boats in tropical waters is reported to last for five
or six years. The following is the formula as developed and
employed by Mr. Weaver: Five pounds white lead, fifteen
pounds of laundry soap, chipped, ten pounds of lamp-black, two
gallons of boiled linseed oil, six gallons of water. Heat to
boiling two vessels of water, having three gallons in each. In
one dissolve the soap and keep the other hot. Thoroughly pul-
verize the lamp-black by stirring and mixing well with one-half
gallon of vinegar. Now add the lamp-black to the linseed oil,
stir, and pour into the soap solution. Add the white lead, mix
the whole thoroughly, using all the water, and apply to cloth
with brush, keeping the paint hot enough to just show steaming
while being used. If the first coating is not sufficient, reverse
the tent and give an application to the opposite side.


For trees not over twelve feet high I found hoop tents
most satisfactory: above that to twenty feet in height I think
sheet tents will prove best; above twenty feet the bell or
sheet will be most satisfactory. As one result of the work a
new pattern of derrick was devised for swinging large bell
tents, which seems more flexible to varying requirements than
the California patterns: or perhaps 1 should designate tents
handled after this plan as box tents, for they are swung in
pairs with the derricks upon the same general principle as
tLe box 'ept; i. e., the type of box >Lnt described in Bulle-
tin 122 of the California Station, the derrick taking the
place of a lifter. The idea that a bell tent might be swung
like a box tent was dlue to Prof. Woodworth. who mentioned
it upon the day of his departure, and the practical working
out of the idea was achieved by the writer's combination of
ideas derived from various sources; Mr. Arthur Weaver's sug-
gestions were especially helpful.
Our derrick consists of a main mast of spruce pine about
thirty-five feet high for trees thirty feet in height, and stands
between the rows to be treated. To each side of it is attached
a gaft twenty-two feet long, also of spruce pine. The foot
of the gaft clasps the mast with arms of oak, being raised
and lowered with double blocks and pulleys exactly after
the manner of a ship gaft. The top of the gaft is double
blocked and pulleyed to the top of the mast, so by means
of its top and bottom attachments the gaft can be raised to any
height, its top many feet above the top of the mast if necessary,
or it can be lowered to reach the ground. Since it can take any
angle of direction also, it may be quickly adjusted to trees of
any height and of variable distances apart. The top of the
bell is attached by pulley near the end of the gaft. Three trail
poles of hickory, each about ten feet in length, are fastened
to one side of the lower border of the tent, their ends being
securely lashed to each other with rope, so when they pull
against each other the rope and not the cloth will catch the
strain. The cloth is caught up and bagged slightly at these
points of union of the trail poles as additional protection against


tearing. The center of each of these trail poles is connected
with the top of the gaft by pulley, and thus the border of the
tent to which they are attached may be elevated to any height,
the opposite border swinging free, within reach, near the
ground. A trail rope is attached to each of the trail poles. All
pulley ropes belonging to the apparatus are secured to cleats on
the mast.
In operation, when the main mast, on rollers or wheels,
has been placed in position, the height of the tree to be fumi-
gated and its distance from the mast are noted, and the foot
of the gaft is raised or lowered to the point of greatest advant-
age as learned from experience. A similar adjustment
is made of the top of the gaft. The top of the tent is next
drawn fully up and then the three trail poles; the hanging
free edge near the ground and as much of the border as pos-
sible is now brought into position, and the top of the gaft
lowered some if necessary. Slack is now given to the trail
poles and a man at each trail rope so pulls the pole to which
his line is attached that the whole tent drops into position
over the tree. The lower border of the tent must be extra
strong to avoid tearing; it is best bound with rope. To remove
the tent from the tree the procedure is almost exactly
reversed. With men trained to work together, the tent may
be lowered over a tree in seven or eight minutes and removed in
about five. Since the operation of removing the tent from one
tree raises it almost in position to drop it upon the next, the
time required for changing will not be the sum of eight and five
minutes, but the last five minutes is divided between the two
trees, removing from the one and at the same time getting
almost in position to lower upon another by a quick adjustment
of the angle of the gaft, it requiring less than eight minutes to
cover a tree from this position. The apparatus requires four
men, one of whom may be the fumigator if he has his mate-ials
weighed out beforehand. A gang of four can operate about
four tents or two derricks, if the rows are not more than twenty-
five or thirty feet apart. This gives forty minutes time to the
tree and allows ten minutes for shifting of the tent. In order


to realize this expeditiousness in practice all apparatus must be
in perfect working order and repair and the men trained to
handling it. The results secured in my practice satisfied me that
this would be a reasonable estimate, for it was done often
enough in this time with our then imperfected apparatus to
justify such a conclusion. Full specifications and illustrations
of the derrick at work will be published later on in bulletin form.
Some determinations suggested by Prof. Woodworth and
made by Prof. Miller, of the Chemical Department, are oT
interest and importance. He found that one ounce of sul-
phuric acid and one ounce of water, mixed and cold, when
added to one ounce of potassium cyanide, yielded 428.4 cubic
inches of gas; that one ounce of sulphuric acid and one ounce
of water, mixed and added immediately, while warm, to one
ounce of potassium cyanide, yielded 467.9 cubic inches of
gas, greater by a little more than nine per cent. than with a cold
mixture of water and acid. Mixing the acid and water, there-
fore, only as used, means a saving of six or seven cents per
tree on large trees requiring two pounds of cyanide. He fur-
ther determined that a greater proportion of acid did not mate-
rially alter the results, and that ammonia seems not to be.
formed immediately after the reaction, under laboratory condi-
A number of experiments were made with citrus twigs,
orange, lemon, pomelo, etc., infested with white fly, to deter-
mine the susceptibility of the insect to the gas, dose of chem-
icals to use, length of time necessary and most favorable tem-
perature for treatment, influence of moisture being present upon
the leaves when fumigated, etc.
It was found that the insect in its larval and pupal stages
is very readily killed by a much lighter dose of gas than is
commonly used against the black scale in California: in fact,
our field practice with tents demonstrated that we could reduce
it about one-half; that the time should be about forty minutes;
the variation in temperature ordinarily encountered in Florida
seems to be a neglectable factor; moisture did not seem to
interfere greatly with the efficiency of the work, unless the


leaves were almost dripping, when it became a factor of much
disturbance, though not so great as we had thought probable.
Trees were fumigated in the field in warm sunshine, at all
hours of the day, in cloudy weather and at night. We observed
but little injury to trees or foliage if fumigated at night, during
cloudy weather, early in the morning or late in the evening.
Trees fumigated after 9 a. m. and before 4 p. m. in sunshine
were invariably somewhat injured, some of the younger limbs
dying back and all of the leaves usually shedding. The fallen
leaves were all replaced by new growth in a few weeks and no
permanent injury done, but the crop upon such trees was notice-
ably reduced. The dropping of leaves from a tree in Florida
has comparatively little significance, the trees, instead of dying,
as they sometimes do in California, putting on new foliage and
going along as if nothing special had happened. However, the
burning of limbs and injury to bloom is another matter, and,
therefore, midday fumigation can hardly be practiced. While
some defoliation occurred with trees fumigated at other times
than midday, even after night, it was not strikingly noticeable,
nor was damage to limbs or crop of sufficient amount to be
detected after a few months. Some of this work was done as
late as February 18, when the blossoms were beginning to open,
some of them being well expanded. The bloom seemed unaf-
fected by the treatment unless the work was done with the sun
at high meridian.
The white fly seemed practically exterminated upon the
treated trees. In examining hundreds of leaves from dozens
of trees about ten days after they were fumigated, and covering
thousands of insects, I was able to find but a single living speci-
men. If a grove was segregated from all others, I have no
doubt that one fumigation would render it so nearly clean that
it would need no additional attention for two or three years.
The great hindrance to its becoming a practicable remedy is
that but few groves are so isolated that the fly will not come
to them from neighboring groves, and since the insect seeks
young and tender growth for egg-laying purposes, there is, per-
haps, some tendency for it to go to trees that have been fumi-


gated and are therefore putting out new growth. Under ordi-
nary circumstances, the insect is not a great traveler, though
winged, and will often take a whole season, extending over
three full broods to spread over a ten-acre grove: its progress
will be marked by the trees showing sooty mold.
Special observations were made to determine the effect of
the gas upon lady-bugs. On the afternoon of January 22,
seventy-two lady-bugs, almost all Chilocorus bivuiilcrus, which
had fallen to the ground under fumigation treatment, were
placed in a shallow tin box and left until January 23 : at 9:30
a. m. of the latter date seventy beetles were in the box, a few
of them active: at 4 p. m. sixty-six remained in the box, about
a dozen of them showing signs of activity. At 8:45 a. m.
January 24, sixty-two lady-bugs were in the box. and sixty at
12:4o p. m.: the sixty never exhibited signs of animation, all
being observed to be dead several days afterward. January 24.
by i p. m. another lot of one hundred-seventy-one fallen bugs,
nearly all of the same species as before, was collected and kept
in the same manner as the first ones. January 25 at 4:30 p. m.,
one hundred-sixty of these were dead, sixteen out of the lot
having recovered. In the first lot, sixteen per cent. of the whole
revived, in the second lot about nine per cent.
Since fumigation does not destroy fungous growths many
growers will prefer giving it a trial before using a caustic spray.
No matter what style of tent is used, when it is in position
a few shovels-ful of earth are thrown on the bottom to holcl i
in place and render it gas-tight around the base. The generating
vessel is set under it, as near to the tree trunk as possible,
and the water is poured in, then the acid; the dose of cyanide,
wrapped in paper, is next dropped into the vessel and the opera-
tor, carrying the edge of the tent with him on his back, quickly
steps away, holding his breath and letting the tent fall into posi-
tion as he does so. A shovel-ful of earth is then thrown upon
that part of the tent border just dropped and everything is
left undisturbed for forty minutes.
The following table shows the amounts of chemicals used
for different sized trees by the Horticutural Commissioners of


Riverside County, California. These amounts are intended
for the destruction of scale insects and can be reduced fifty per
cent. or more in quantity if it is not specially desired to kill other
insects than white fly:

Height of Diameter of Cyanide C. P. Sulphuric Acid,
Tree. Tree. Water. (98 per cent). (66 per cent).

Feet. Feet. Ounces. Ounces. Ounces.

6 4 2 1 1
8 6 3 1/ i '
10 8 5 2/2
12 14 11 5
16 16 17 8
20 16-20 22 10 12
20-24 18-22 30 14 16
24-30 20-28 34 16 18
30-36 25-30 52 24 28

The cost of fumigating trees, labor included and not con-
sidering the cost nor wear of the tents, is about equal to the cost
of giving the same trees three sprayings with resin wash. Low,
squatty trees, such as are grown on C. trifoliata stocks, with
their branches hanging to the ground, are of the shape that
should be sought when it is intended to fumigate them regu-
The precautions to be observed in handling the chemicals
are given in the succeeding section on nursery fumigation work.

The Nursery Situation.

No provision is made by the State for the inspection of
nurseries, hence there is no way of officially determining their
exact status throughout the State. My knowledge of their con-
dition must necessarily come through chance channels and the
information I receive is often too unreliable to warrant any
public statement regarding it. The reputation of the respective
nurserymen for reliability of statement, care in handling their
goods and the general condition of the neighborhood in which
they are located are the only guides that can be-depended upon
in choosing from whom to purchase. The safest practice for all

r 40




parties, customers and nurserymen alike, will be to handle, in
the future, only stock that has been defoliated and cut back. I
believe that citrus stock prepared in this way is safer from
white fly than is inspected and fumigated peach stock from
scale, when shipped from a San Jose scale neighborhood. When
fumigation with hydrocyanic acid gas is added I regard the pro-
tection as perfect. Fumigation should always be practiced dur-
ing the spring and summer months and is best never omitted.
If stock is shipped during spring or summer, every vestige of
leaf should be carefully cut away so as to make certain that no
unhatched eggs remain, since these are not readily destroyed
by fumigation. Fumigation is undoubtedly effective in
destroying the adults and larvae. Dipping and even soaking
infested leaves for considerable periods of time in tobacco
decoction, Rose-leaf Insecticide, Good's Potash Whale Oil Soap
No. 3, Good's Potash Tobacco Soap No. 6, Leggett's Whale
Oil Soap Compound and resin wash have been tried, but with-
out satisfactory results. The odor accompanying most of these
washes is objectionable and even when the leaves are left
immersed in them for considerable periods of time, protected
larvae escape injury; thus a leaf with a blister or cavity pro-
duced by scale or red spider which was netted over with a
spider's web and threads of the sooty mold was submerged for
ten minutes in a solution of Good's soap No. 3, one pound to
two gallons of water, without killing the larvae sheltered
beneath the web as shown by an examination made 72 hours
To determine the dose of potassium cyanide (KCN) nec-
essary to give the correct amount of gas to kill the white fly
larvae in an air-tight fumigatorium, I commenced by using one
gramme of KCN to 15 cubic feet of space for thirty minutes
time. An examination made three days later revealed that
about 47 per cent. of the larvae had been killed. One gramme
of KCN used for I I, 9 and 7 1-2 cubic feet, respectively, for
the same length of time showed constantly decreasing percent-
ages of living larvae. One gramme of KCN to 6 1-2 cubic feet
of space allowed but one larva out of many that were examined


to come through alive. One gramme to 6 cubic feet seemed to
kill everything but to make the dose more certain one gramme
to 5 3-4 cubic feet was adopted as the standard dose and has
been repeatedly tried, always giving the uniform result of kill-
ing all larvae and adults. This dose requires about 17 grammes
or 3-5 of an ounce of KCN for every Ioo cubic feet of space, or
I70 grammes, that is about 8 ounces, Avoir., for every I,ooo
cubic feet of space.
The following experiment was made to determine the effect
of fumigation on the true eggs. A potted lemon bush, entirely
free from white fly, was confined under a cheese-cloth cover and
several hundred adult flies were captured and liberated inside
the cover. At the end of 48 hours the leaves were covered with
thousands of eggs, several hundred of them occurring on each
of several leaves. The bush was then fumigated for thirty min-
utes with the standard dose, or one gramme of KCN to each
5 3-4 cubic feet of space enclosed. The bush was then kept
in an unused recitation room, into which no adult fly could pos-
sibly enter by accident. After three weeks it was found that
about 5 per cent. of the eggs had hatched and the larvae had
set upon the leaves. As there could be no possible error as to
each egg having been subjected to the gas it is evident that a
stronger dose is necessary to kill them. Had the plant been
left in full sunshine it is probable that a yet larger percentage
of the eggs would have hatched. The bush was severely
burned by the gas and it appears that the vet undetermined dose
which is necessary to make certain the killing of the egg, is
equally certain to damage citrus plants. During the period of
heaviest nursery shipments from December 15 to the ist of
March, there are no unhatched eggs, hence no danger exists
because of them during this period. Since the eggs are never
laid elsewhere than upon the leaves, defoliation and cutting
back of the terminal growth removes all possibility of danger
from unkilled eggs at all times.
No citrus leaves from an infested nursery should be
allowed to get into the moss used in packing. Such leaves
could hardly be a source of danger except when harboring well


grown larvae or pupae but, as before mentioned, both larvae
and pupae will live for several days upon detached, drying
leaves in the laboratory: and if they were packed in damp moss
it is very probable that nearly matured ones would issue as
adults even as long as three weeks or a month after they were
This spring two lots of trees, six in each, infested with
white fly larvae, were fumigated with the standard dose of
KCN and set upon the Station grounds without being defoli-
ated: most of the leaves fell as a result of the fumigation but a
few adhered carrying the dead larvae. No white fly developed
on these nor was there any injury to the stock appa-
rent. due to the fumigation. Another dozen similar trees,
not fumigated and planted out at the same time, held a fraction
of their leaves, the white fly appearing upon them at the regular
My fumigating box has never been packed full of stock
with the foliage remaining upon it and it may be doubted if
the dose I use is sufficient to kill all larvae under such circum-
stances: but I think there can be no doubt that in case it were
filled as full as possible of defoliated stock all chance larvae
present would be killed.
The accompanying photograph shows a fumigating box
of similar pattern to the one in use on the Station grounds.
It consists of an inside and an outside box, with an intervening
space of six inches filled with sand. The outside box needs no
floor but the inside one should be floored to prevent partial
absorption of the gas by the moist, earthen floor. The lid which
is hinged and lifted by means of double blocks and pulleys is
made of two thicknesses of wainscot or flooring with a layer
of raw-hide building paper between. Two good coats of lead
and oil paint should be applied to the cover inside and out. An
air-tight joint is secured between the cover and the box by
running around the under side of the cover, which overlaps tTie
edges of the inside box, a pine strip, 2 inches in depth, which
thus dips down into the sand. It is best to have a small door
about I foot square in the bottom of the box, on one side and as

654 BULLETIN NO. 67.

near the center as possible. This door furnishes safe means for
introducing the chemicals; its edges should fit against a cushion
of felt or burlap; it is tightly pressed against the cushion by
some form of sliding wedge driven into place by a smart rap
with a hand mallet. If a slatted platform is constructed six or
eight inches from the floor to support the plants, the gas being
generated below it, diffusion will be comparatively uniform and
results with both trees and insects more satisfactory than can be
otherwise secured. A tight box-hood should cover tTie upper
half of the generating box which is a foot in each of its three
dimensions, the lower half of it being left open, thus forcing the
gas out beneath the slatted floor.
The following dimensions will give a box of 99 cubic feet
capacity (practically Ioo cubic feet) which will be one of the
most convenient sizes. Length of the inside box, II feet;
width, 3 feet; height, 3 feet. Length of outside box, 12 feet;
width, 4 feet; height, 3 feet.
To charge the box with gas, fill it with the trees to be
fumigated and close down the lid; if the sand is not sufficient
in quantity, fill in enough to make a tight joint certain. Now
through the trap door introduce into the generating box the
generating vessel, which should be of earthenware, China or
glass-a glass fruit jar will do; with a glass graduate, measure
out in liquid ounces a number of ounces of sulphuric acid
(H2S04) greater by half than was used of ounces of cyanide,
or in this case, add to 3-5 ounce equal .6 ounce, 1-2 of itself,
or .3 and 9-1o liquid ounces is obtained as the correct amount
of acid. Of water, use 1-2 more liquid ounces than of acid; in
this case, 9-o1 plus 1-2 of itself equals .9 plus .45 equals 1.35 or
I 1-3 ounces (nearly). First pour the water in the generator,
next the acid. The cyanide should be weighed out beforehand
and kept, each dose wrapped in paper, in an air-tight receptacle.
The dose, paper and all (use as little paper in wrapping as
possible) is dropped into the water and acid, the door being
immediately closed and wedged into place. After remaining
closed for 30 minutes the upper lid is raised. The residue in
the generator consists of sulphate of potash, sulphuric acid and






water; should it come in contact with the skin or clothing, T
will corrode and is best buried in the ground when the generat-
ing vessel is emptied. It should never be forgotten that cyanide
of potassium is a most deadly poison and that a very minute
particle of it introduced into the moutl will cause immediate
death. It is best to use forceps in handling it; never allow
it to touch cuts or open sores on the hands. It should be kept
away from children and uninformed persons. The gas is the
deadliest known, and while no fatalities have ever attended its
use as an insecticide, such have occurred in chemical Tabora-
tories, and the greatest caution should be observed in working
with it. For fuller information concerning fumigating appli-
ances and methods of procedure, the reader is referred to
Prof. W. G. Johnson's Fumigation Methods, published by the
Orange Judd Co., New York.

Insects Sometimes Mistaken for White Fly.

Lecanium hesperidum Linn.-The immature stages of this
insect are perhaps more easily, or, at least, are more frequently
mistaken for white fly than any other species. The flat, oval
scale upon the leaf so nearly similates the larva of white fly
that the ordinary observer is quite excusable in being deceived
at first sight. However, the Lecanium is more elongated than
Aleyrodes citri and, relatively, it broadens much more distinctly
towards the posterior extremity. The length when full grown
is more than twice that of the mature white fly larva, the
width being not quite double that of the latter. The body is
distinctly notched inward at the posterior end, a formation
differing from that in case of white fly. The young are found
on the stems and tender branches of various plants (a position
never occupied by white fly larvae so far as I have been able to
discover) as well as upon the leaves. When upon the leaves,
the young tend to range themselves beside the mid-ribs and
principal veins, a habit which again disagrees with that of
A. citri. The scale is commonly spoken of as the turtle-back
or soft scale. The dorsal skin may be called yellowish or red-


dish brown, inclining to dark, in some specimens almost to a
shining black toward the center. This insect agrees with white
fly in causing an excessive growth of sooty mold upon its host
plants. (Plate I, fig. II.).
Nearly related species of Lecanium, such as L. oleae (Ole-
ander is one of its common food plants) are found on various
plants, being always followed by sooty mold.
Aleyrodes floridensis Quaintance.-The Guava white fly is
found sparsely upon orange. It is a smaller insect than A. citri
and the larva is surrounded by a fringe of glassy, waxen rods,
conspicuous enough when once noticed, but not readily
observed unless looked lor. The insect does no damage to
orange. It has been collected from many parts of the State
upon guava, which it infests seriously, and several years ago
Prof. J. H. Comstock collected it at Arcadia, Fla., on "alligator
pear."* A few weeks ago it was sent to me from Arcadia by
Mr. E. A. Thomas, taken Trom orange trees that had been
planted out, according to his statement, for one year. There
can be no reasonable doubt that the insect went to his trees from
guavas or "alligator pears" in the neighborhood. (Plate I. fig.
Ceroplastes floridensis, the white wax scale, often causes
patches of gallberry bushes to become very black with sooty
mold, the appearance frequently being ascribed to the presence
of white fly.
Aphis and many other insects which secrete honey dew
and hence are followed by sooty mold have been supposed
at one time or another to be white fly.
The papaw white fly, Aleyrodes variabilis, has been
received once or twice under the supposition that it was the
orange white fly. Several species of Aleyrodes may be readily
mistaken for it.

*Bnlletin U. S. Dept. Agr. Division of Entomology, Technical
series No. 8, (1900) p. 27.


The Outlook.

As already indicated, the insect is known to be established
in fourteen different counties in the State. I have reasons for
thinking that it occurs in several other counties than these, but
no resources are at my disposal to make a thorough inspection
of the State and determine authoritatively its exact distribution.
I feel sure that wNithn two years more every neighborhood that
was infested before the freeze will discover that it is still
infested. Where the insect has become well established by three
or four year's of breeding it is well nigh or quite impossible to
exterminate it. It is seldom discovered until four or five years
have elapsed after its introduction, that is,not until measures of
extermination are very apt to prove futile. At the time of
discovery it will appear to-be confined to a small area, in most
cases from a few bushes or trees to a quarter of an acre, but in
reality it is sparsely scattered over a territory having a radius oT
from a quarter to a half mile from the center of infection. I
have proved this too many times to be deceived; yet many
groves and yards in a town may be infested for several years
without the insect's finding its way into groves not more than
a mile or two from town.
With the habits of the insect well known and its distribu-
tion once authoritatively established, its spread over the State
could be greatly retarded but not finally prevented. Fifteen or
twenty years may yet remain before the insect will have found
its way into every neighborhood in Florida, but this it will cer-
tainly do in time. This certainty of eventually getting it should
cause no indiference, discouragement or carelessness on the
part of any neighborhood or individual; rather ought it to deter-
mine everyone to postpone the evil day as long as possible. Five,
ten or fifteen years of immunity from the fly, with consequent
bright, early maturing fruit of high quality, when competition
with other parts of the world will be close and a large part of
Florida handicapped because of the insect, is a reward well
worth the price of a diligent and persistent lookout to obtain.
Special caution should be observed to receive no improperly pre-


pared nursery shipments from any suspicious quarter; and
when the insect appears in any neighborhood the preceding
section of this bulletin upon methods of dissemination should
be carefully studied and the suggestions there given to restrict
its spread should be put into practice at once.
Will the orange business be ruined by the insect? No,
certainly not; granting that ten years from now the State will
receive three-fourths of a million or even a million dollars less
per annum than it would receive if the insect were absent,
Florida oranges can still be grown at a profit as has been proved
by numerous growers through many years of trial. If groves
in the heart of the present white fly districts are quoted at
prices but little if any lower than if they were located outside
of them, they will continue to be paying holdings there and
elsewhere, notwithstanding the presence of the fly. No insect
of this nature has ever withstood the skill of man in the end,
destroying a great industry, and white fly is not so difficult
to control as many believe. Natural enemies, restoring
Nature's balance, will appear in time, and until then the vari-
ous means of control already known will be employed by an
increasing number of growers. Legislation could be helpful in
certain ways, chiefly in increasing the resources of the Entomo-
logical Department for experimental work and thus enabling it
to introduce the important diseases of the insect into such sec-
tions as do not at present have them. The establishment of
quarantine regulations would be of questionable utility unless
an appropriation of sufficient magnitude were made to maintain
a large force of inspectors, and the exercise of all possible vigi-
lance on their part would still be less effective than the simple
observance by every purchaser of the recommendations em-
bodied in this publication. So far as the grove problem is
concerned, as previously observed, the sentiment of our peo-
ple is sharply divided regarding wise insecticidal practice, and,
until it can be united, the enforcement of prescribed methods of
treatment by State officials could only be a source of friction
and irritation. Those who believe that treatment of all infested
groves should be enforced by law should become home mission-


aries for the next few years, satisfying the majority of their
neighbors that such treatment pays,-a task which I believe can
be readily wrought by two or three seasons of practical demon-
stration with spray pump or fumigating tent.
The ultimate distribution of the fly will be over all the Gulf
States northward to an isothermal line running somewhere
through northern Georgia and westward; California is very
likely included in the infested territory now, but it is in the
moist gulf regions that the ueprecations of the insect are to be
feared. Citrus fruits will be profitably produced, notwith-
standing its presence, wherever climatic conditions are suitable.


In the prosecution of this investigation I have freely con-
sulted the writings of Riley & Howard, Webber, Morgan,.
Woodworth. Ouaintance and others. Valuable information
and suggestions have been given me from time to time by Mr.
A. J. Pettigrew, Prof. H. H. Hume, Prof. C. W. Woodworth,
Mr. F. D. Waite, and others too numerous to mention. The
drawings for plates I and 2 were made by Miss L. McCulloch,
under my supervision. The drawings for plate 6 were made
by Prof. Cockerell. The negatives for plates 4 and 5 were taken
by me and the prints were made by Prof. Hume. The first
three figures of plate 3 are wholly the work of Prof. Hume,.
while Fig. 4 of the same plate is credited to Prof. H. G. Dorsey.

Summary of Important Facts and Recommendations.

I. White fly, an insect of unknown origin, is probably our
worst orange pest where it now occurs. It is known to be estab-
lished in 14 counties in Florida and probably exists in a num-
ber of others.
2. There are three annual broods of the insect of which
the first two broods of adults, one occurring in March, April and
May and the second in June. July and August. respectively, are
well defined and distinct; the third brood occurs in greatest


aries for the next few years, satisfying the majority of their
neighbors that such treatment pays,-a task which I believe can
be readily wrought by two or three seasons of practical demon-
stration with spray pump or fumigating tent.
The ultimate distribution of the fly will be over all the Gulf
States northward to an isothermal line running somewhere
through northern Georgia and westward; California is very
likely included in the infested territory now, but it is in the
moist gulf regions that the ueprecations of the insect are to be
feared. Citrus fruits will be profitably produced, notwith-
standing its presence, wherever climatic conditions are suitable.


In the prosecution of this investigation I have freely con-
sulted the writings of Riley & Howard, Webber, Morgan,.
Woodworth. Ouaintance and others. Valuable information
and suggestions have been given me from time to time by Mr.
A. J. Pettigrew, Prof. H. H. Hume, Prof. C. W. Woodworth,
Mr. F. D. Waite, and others too numerous to mention. The
drawings for plates I and 2 were made by Miss L. McCulloch,
under my supervision. The drawings for plate 6 were made
by Prof. Cockerell. The negatives for plates 4 and 5 were taken
by me and the prints were made by Prof. Hume. The first
three figures of plate 3 are wholly the work of Prof. Hume,.
while Fig. 4 of the same plate is credited to Prof. H. G. Dorsey.

Summary of Important Facts and Recommendations.

I. White fly, an insect of unknown origin, is probably our
worst orange pest where it now occurs. It is known to be estab-
lished in 14 counties in Florida and probably exists in a num-
ber of others.
2. There are three annual broods of the insect of which
the first two broods of adults, one occurring in March, April and
May and the second in June. July and August. respectively, are
well defined and distinct; the third brood occurs in greatest

660 BULLETIN NO. 67.

numbers in September and October, its time limits being poorly
defined. The insect shows a tendency to continuous breeding
during the last half of the year.
3. The eggs are laid only upon the leaves and the young
are motile for a few hours after hatching. When wandering
ceases, the larvae fasten themselves to the under surfaces of
the leaves and imbibe the sap, at the same time covering the
upper surfaces of the leaves vertically beneath them with a
coating of honey dew in which a smothering, black, sooty mold
4. The fruit is delayed several weeks in ripening and its
sugar and acid content is much reduced; it becomes covered
with black mold, necessitating hand or machine washing to
prepare it for market, and its carrying qualities are often much
injured by such preparation. The annual loss inflicted on the
State amounts to hardly less than a quarter of a million dollars
and will increase unless the insect is fought.
5. The insect is scattered by nursery shipments, by wind
currents, by being carried in covered vehicles, in railway
coaches, etc. The motile young may become entangled in the
feathers of birds and adult flies are undoubtedly occasionally
carried by the same means.
6. White fly has few insect enemies, but two fungous dis-
eases are very efficient in suppressing it under favorable condi-
tions. In close planted groves, surrounded by hammock woods
near the coast, these diseases are depended upon wholly by some
growers in South Florida to control the insect. It does not
become so numerous in open planted groves upon high pine
7. Spraying against the white fly is not often abandoned
'by growers who have once tried it. The most favorable time
for spraying is during the winter larval period. At least two
thorough sprayings should be made during the winter. Sum-
mer spraying is sometimes useful but the materials should be
carefully chosen.
8. Resin wash is a very satisfactory spray for winter use
but should not be used while the fruit is young. A potash whale


oil soap spray may be safely used, at proper strength, any time
except when the trees are in bloom. Kerosene emulsion, caus-
tic soda solutions of sulphur and salt, Thrip Juice and Mont-
gomery's insecticide are all useful to a certain extent and will
be sometimes chosen according to the personal preferences of
the grower. There seems to be a general and well founded
opinion that a good potash whale oil soap is less apt to cause
injury to the tree than most insecticides.
9. Fumigation of infested groves is effective and some-
times useful, but at present can only be recommended for use
in particular instances.
10. Infested nursery stock is rendered wholly safe by being
defoliated, cut back and properly fumigated.
I I. The insect will eventually spread over the entire citrus
belt but its march can be greatly retarded by care in purchasing
and by vigorous repressive measures where it is already estab-


In response to an inquiry addressed to Prof. T. D. A.
Cockerell, formerly connected with the New Mexico Experi-
ment Station and at an earlier time Stationed in Jamaica with
the Imperial Department of Agriculture for the West Indes, he
kindly offered to make the comparative study here given of
A. citri and its allied forms, thinking such a study might
throw some light on its origin. The recognized standing of
Prof. Cockerell as a comparative anatomist and the large
amount of information in his possession relating to this family
of insects gives instant interest to anything written by him on
such a question. Whether or not his conclusions ever prove
to have been correct, since they direct the attention of entomol-
ogical workers in other parts of the world to the subject, thereby
making possible the discovery of the insect's original home, the
thanks of Florida are due him for his effort.

662 BULLETIN NO. 67.

(Aleyrodes citri) AND ITS ALLIES.

The genus Aleyrodes (often spelled Aleurodes) was first
distinguished and named by Latreille in his "Histoire Naturelle
des Crustaces et Insectes," Vol. XII. p. 347. In this work pub-
lished in 1804, there is given a description of the genus, the type
of which is the Tinea proletella of Linnaeus. This species,
which lives in Europe on leaves of Chelidonium majus, was
made the subject of an excellent memoir by Reaumur (Mem.
Ins., Vol. II, pp. 302-317, PI. XXV, figs. 1-7), and conse-
quently was quite well known at the time of Latreille's publica-
tion, though it had been erroneously placed among the
A close ally of this A. proletella is A. brassicae, Walker,
1852, which occurs on cabbage. This is said to be hard to dis-
tinguish from proletella in the adult, but the larva (pupa?) is
long, while that of proletella is round-oval. In 1868 Signoret
published a revision of the then-known Aleyrodidae, describing
seven as new. Most of the species were European, but two
were known from Chili, two from the United States, and one
from Mauritius. In 1896 Maskell (Trans. New Zealand Insti-
tute, XXVIII.) gave a list of all the Aleyrodidae known at that
time, numbering 66. Of these, 22 were described as new.


The adult Aleyrodidae are small, four-winged insects, very
similar to one another, except for the fact that some have the
wings variously spotted and banded. The pupae, however, pre-
sent very strong distinctive characters, and are largely used in
classification. These pupae are small, oval objects attached to


leaves, usually to the lower surfaces, and in general resemble
the smaller kinds of scale-insects. Under a compound micro-
scope one is able to see certain characters which greatly assist
in the identification of Aleyrodid pupae. On the back toward
the hind end, is an orifice of a more or less triangular or
rounded shape, known as the vasiform orifice. In this is seen a
lid-like structure, the operculum, and a more or less tongue-like
object, called the lingua. The margins of the pupae are also
variously sculptured, and offer good characters.
With a lens, one notices the color, shape and convexity of
the pupa, and the character of the waxy secretion, if any. This
secretion covers the whole pupa, but more often it forms a
fringe around the sides.

Divisions of the Aleyrodidae.

At present, only two genera are recognized in the family.
Aleyrodes, Latreille, includes the great majority of the species,
these having the main vein of the wings not bifurcated towards
the end. In 1892 Douglas separated the genus Aleurodicus
which contains those species having the main vein of the wings
bifurcated. This is a perfect valid distinction, but care must
be taken not to mistake a fold which often occurs in the wings
of Aleyrodes for a branch vein. It has not been considered that
Aleurodicus can be distinguished from Aleyrodes by the pupa,
but I believe it has sufficient characters in this stage also. These
are found in the short, broad operculum, combined with a very
large lingua, which has two or four bristles at its end. The
pupa also has large submarginal orifices, especially in the
abdominal region, and the margin is likely to exhibit bristles at
rather distant intervals.
Having regard to these characters, I believe that the fol-
lowing, hitherto referred to Aleyrodes, may be safely trans-
ferred to Aleurodicus.
(1.) Aleurodicus altissimus (Aleurodes altissima, Qpain-
tance, tom. cit p. 20.)
(2.) Aleurodicus perseae (Aleurodes perseae, Quaintance,
tom. cit., p. 32.)


(3.) Aleurodicus holmesii (Aleurodes holmesii, Maskell,
tom. cit., p. 435.)
All the species of A leurodicus belong to the warmer parts
of America (North and South), except A. holmesii, which is
from Fiji. I suspect that the latter was introduced into Fiji
from South America, along with the guava (Psidium) on
which it lives.
Although Aleyrodes, after excluding Aleurodicus, includes
a great many diverse types, it has not yet been subdivided. An
examination of the vasiform orifice, lingua and operculum
brings out the following facts:
(I.) There is a group, apparently exclusively American, in
which the orifice is rather elongated, and the lingua is long and
narrow, and usually strongly crenulated. This includes such
forms as A. erigerontis, A. nicotianae, A. vittata, A. variabilis,
A. pergandei A. fitchi and A. ruborum.
(2.) A small American group, allied to this, has the lingua
enlarged distally, with a distinct terminal joint. This includes
A. pergandei A. fitchi and A. ruborum.
(3.) A third American group, found principally on the
oak, has the pupa very dense, quite black, with the orifice elon-
gated. The margin of the pupa is peculiar, and there is a white
waxen fringe. A. melanops (figs. 2, 3, 4) and A. perileuca (fig.
5) are examples.*
(4.) There is a group of the Old World, from India to
New Zealand, in which the orifice is usually short, sometimes
broader than long, and the lingua is much abbreviated. Exam-
ples are A. cotesii (India), A. croseata (Australia), A. euge-
niae (India), A. aurantii (India), A. fodiens (New Zealand)
and A. piperis (Ceylon).

Aleyrodes perileuca. n. sp.-Pupa perfectly black, 1250 micromil-
limeters long. of the usual oval shape, with a very narrow regular
fringe of straight white waxen ribbons, about Ioo micromillimeters long.
A sharp, elevated, submarginal keel; dorsum strongly longitudinally
keeled, the abdominal portion with transverse ridges making the seg-
ments. The dorsal keel in the thoracic region is sharp, but in the ab-
dominal region it is broad and rounded, with its surface irregularly tes-
selate, and is crossed by six transverse narrow antero-posteiorly corru-
gated bands. Vasiform orifice shovel-shaped. Marginal area with very


Other groups are suggested by various species, but do not
seem to be so clearly defined. Curiously, A. fioccosa and A.
stellata, from Jamaica, seem to be related to the Australian
series of A. stypheliae, A. nigra, A. limbata, A. hirsuta and A.

Aleyrodcs Citri.

The white fly, or citrus mealy-wing, was described in
detail, with excellent figures, in Insect Life, Vol. V, (1893) pp.
219-226. Unfortunately, however, the detailed characters of
the pupa were not given in such a manner as to permit ade-
quate comparison with other species. Prof. H. A. Gossard has
kindly supplied me with abundant material on leaves of Cape
jessamine (Gardenia) from Florida, and I am able to give dia-
grams of the pupa (fig. 7-) and of the vasiform orifice (fig. 6).
It will be seen that the vasiform orifice is broader than long,
and the lingua is short and broad. These characters are not
those of the typical American groups, but agree well with the
Asiatic group, No. 4 above.
On examining the other characters of the pupa, we find
three deep furrows (fig. 7, a,a,a, and A,), one on each side, and
one at the caudal end. At the distal end of each furrow is a
somewhat star-shaped opening. Such structures as these I find
described only in two species, namely, A. eugeniae, Maskell,
tom. cit., p. 430, and A. aurantii (eugeniae var. aurantii, Mas-
aurantii (which appears to be a valid species) occurs abun-
dantly on leaves of orange in the northwest Himalayas.

numerous regular radiating furrows, the areas between them minutely
punctured. Margin very regularly crenulate. No dorsal section what-
ever. The conical black larval skin was found in one example on the
back of the pupa, but ordinarily it falls away.
Hab. Solitary on the upper side of leaves of live oak; Cuero,
Texas, June 2, 1898. (C. H. T. Townsend); La Jolla, San Diego Co., Cal-
ifornia, Aug. 1901, (Cockerell).
Aleyrodes melanops, n. sp.-Pupa black, similar in structure to A.
perileuca, but larger (about I I-2mm. long), broad-oval, with the white
fringe much longer and curled over, so as to be strongly convex above.
Hab. Solitary on the upper side of leaves of oak (Quercus), at
Alpine Tavern, Mt. Lowe, California, Aug. 19go. (Cockerell.)


The Original Home of Aleyrodes Citri.

I believe that Aleyrodes citri is a native of China or some
neighboring country for the following reasons:
(I.) It's affinities seem to be wholly with an Asiatic and
Australasian group, and particularly with a species found on
orange in the Himalayas.
(2.) Orange trees have been brought to Florida from
China, and the Aleyrodes would be very easily carried with
(3.) Florida has had, at least as long as the Aleyrodes,
two scale-insects of the orange, which are almost certainly
Asiatic and very likely Chinese. These are Parlatoria pergan-
dei and Mytilaspis gloveri. These were probably brought over
at the same time as the Aleyrodes.
(4.) A. citri occurs also on the Cape jessamine (Gardenia
lorida), which is a native of China.
(5.) A. citri multiplies excessively in Florida, indicative
that it is probably not American. The American species of
Aleyrodes are not commonly harmful. In Arizona I found an
Aleyrodes of a native type living upon the oranges but it was
not doing any harm or multiplying excessively. This insect
(described in Science Gossip, May 1900, p. 366,) appears to be
only a variety of Aleyrodes mori, Quaintance. It may be called
A. mori var Arizonensis.
[In the article just cited, owing to an editorial blunder
two paragraphs are run together, making nonsense, page 367,
first col., line 14, dele "They are," and begin a new paragraph.]

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