Spraying for white flies in Florida


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Spraying for white flies in Florida
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Yothers, W. W
United States. Department of Agriculture, Bureau of Entomology ( Washington, D.C )
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oclc - 27941763
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Full Text
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L 0 HOWARD F.na.,m.,I..i, and (. hF l 4 Bureau




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Bl. V, I U OF E.XTO IOtOnr) .

L. 0. HOWARD, Il. l,,!i ,t(r otil C'ifcf of Bureau.
c. L. MIARLATT, E:,ill,'i,,l','ql and Acting Chif in Ab.encr fif Chief.
R. S. CI.IFTON, I.'1 re uti"' t..qii.dtInt
W. F. T.sri T. Chi( f .'lrl-.
F. H. Ciii ri L N.1 1. in charge of truck t r,I, and .tIlvtd I" iutod t ve< I in re.Iigailiaona.
A. D. HOPKINS, in charge of forest insect in1 c-.,iintrv,-.
W. D. HUNTER, in J, ,, southern field rrnjp in-. it 111 r.iialfItins.
F. M. \VI i||S IR, in Ili,'ir- of cereal and foragi inr, I' til r.- ionftione.
A. L. QUAINTANCE, in charge of deciduous fruit in.', I i wr, .t1.7'ilion?.
E. F. PHILIPS, in ,i iii c of bee culture.
D. M. Ilo.riis. in rlin, i. of pit1 i, iliin.i prvfld ,if II'll,// fild tork,
ROLLA P. CURRIP, in charge ,! editorial Ci, ,'.
MABEL C'I L un10. in charge of library.


C. L. ni \TT. in rhervr
R. S. WoGLUMi, W. W. YOTIHERS, E. I. S.%szC .1. R. HORTON. P. H. TIrBERLAA:,
C. E. Pi M. in IciN. II. L. SANFORD, BEUI.AH M. Bu.-., prcparator.
J. G. SANDERS, collaborator.

CIRCULAR No. 168. lnuvd AprilN 16. 11i.

United States Department of Agriculture,


L 0. HOWARD. Ent-'m.,,, ,i and Chief of Bureau.


It% WV. W. YoTIIS, lII .'m',,li, .,I I1vi l W .
Citrus trees in l'lorida are subject to inji,, v hv fouIr Species of
while tli-,, only two of wtii, i. however, the citrus white fly (l rodes citri R. & H.) and the cloudy-win-,'1 white fly (A1Y .,,.
nid',ifer, Bri,.,.r), it,' uiitli,'inl ,lii,.ie at the p)rl-vnl time to de-
mani remedial measures. Of the two species considered the citrus
while tly is by f:ar the most injurious.
The citrus white flYv is an introduced pest, haiviii._, been Ir,,,ILrht
to this country from Asia some time prior to 1-T1'. Since its intro-
,duction it has spread over the entire citrus ii.,nii of ithe State and
w,-(%wardl tlirLl- i1 1i the ,;Ilf r,..n i,. At the present time it infests
fullY l61) per cent of the groves in Florida. It occurs on some I'
s|eie.- 11f trees and -;1111 -. the most important hosts I-lIII the (Chil i
nrev's (i ape j,'--.iiiinII., 1ri,'t. and various species of citrus. (O)f
native plainly' the only two li,.l have been reported as bviiiLg seri-
ously iiin feted are the prickly ashl and wild persimmIon.


In 0 h'nItlii inL'_ its life ',v 14- the citrus white fly passes tIhr,,'i.Ih
four -IL','-. viz, ,L',_'. hlarvA.. p,, :i1. and adult.
,. TI-To the unaided e,, the r','.- a ippr..ir as minute particles
of whiri-h dust. Thy are deposited on the i ld,,r-ide, of the leaves.
1it indicate the size of these -'- it has been es-timated that 1I
pl.t'eI end to end volil measure 1 il.. whereas 1 square inch
would contain about a3,l,-4, placed ,.ide by side. When exiunuiel


under a riaiiiifyilig glass. they resemble kernels of wheat in shape
and appear as smooth, polished, green i- h-yellow objects. After
they are deposited, from 10 to 12 days are required for the eggs to
The larva.-The newly hatched larva of the white fly is active,
rv-ciiil'ling that of a scale insect. After crawling for several hours
it settles on the underside of a leaf, inserts its beak, and begins to
take nourishment by .sicking the juices of the plant. To reach
the pupal ,tige it sheds its skin three times, the legs being reduced
to mere rudiments after the first molt. The duration of the larval
stg-es is approximately 23 days.
The pupa.-The pupa closely resembles the last-stage larva, but
at maturity is thicker, more rounded, with a bright red spot on the
back. From 3 to 8 days before emergence the eves of the adult be-
come visible. The duration of the pupal tage varies from 13 days
in the summer to a maximum of 304 days during the fall, winter,
and spring. The larvae and pupae secrete honeydew, which drops on
the leaves and fruit, furniis.liiig nourishment for sooty mold.
The adult.-The iN inged adults emerge from the pupal cases, which
remain attached to the leaves. They collect most abundantly on the
new growth and there they deposit their eggs. A single female has
been known to deposit as many as 250 eggs, but the average is not
more than 150 for each individual. The average life of the adult
is 10 days.
Seasonal history.-The citrus white fly passes the winter in the
pupal stage, the adults of the first brood appearing in maximum
numbers in March or early April, depending upon the season and
location. After the practical disappearance of the last brood there
is a period of about six weeks when adults are scarce. The second
flight, or brood, of adults takes place in June. There is no marked
absence of adults between the second and third broods, owing to the
overlapping of these broods. 'lThe third brood reaches maturity in
August. when the third and last flight of adults takes place. The
eggs depo,-ited by this third brood develop to the pupal condition
and thus they remain on the leaves until the following spring. The
third brood is by far the most numerous, and the larvae and pupa-
following this flight, by the extraction of sap and the excretion of
hnei\ydew upon which sooty mold grows, cause the greatest damage
to citrus trees.

The cloudy-winged white fly may be distinguished from the citrus
white fly as follows: The eggs of the former are dark and have a
reticulated surface. Those of the citrus white fly are greenish yellow

S|'I1A 1INI( 1,1il WHITE 1 II1..S IN Fi0'l1I'\. 3

ainil siiK,,it Thie i,,ti t''ase ,r the liiid\-\ -iii,., white fC1 is thin
:uil ineibrallnouls anld ,iill.i-,.-. after the ,i" ,r.i of the adult,
1-whileh that if the citrus whi iill retail s itsI hape i' I ll-iii 'I It,
aidult-, are eai ily dlif iiguished; the c1oudy-wi,.%.., 1 1iie tlly hias 1h;rk
mnurkiing- on its % i,-. while the ii i.- of ie cit Irus white fly are
purr white. Thi. broods of the cIloudy-wi .' I w hite tly appear abouLt
a it ii iih later than thoI e of the citrus white (ly.

The inijiur\ caused by the citrus adllI cloImudw V lii\ white ki is
nliihiih gi'"lrii thanl is _r,,,,,..illy ~"Iii <'-' .. d. I I,,. i.liil.iL,' occasioned
hb the loss of Isup is conitlealilh and is a serious drain on the trI-,
but is of secondary import alice to the ,l.iri.iLc cauleld by the sooty
1moldh which f,,ll,'s the white fly.
The sooty Iiiilil affects both the fruit, aInd Iea\.-. !1 ,,.k,1iuI,-- the
firiiir r :and o.\ .i-iiIL' tle iI[>[>1,r .ir'i,1 r f 1 t- e latter w itli a I dark-
bri\\ ii coat ing which excludes the -ii1i1lit and .I,, '. and checks the
groI- h. Ti,, reductions in yield from the white flies and sooty ii rlil
is variously estimated i I to be 1'i1i .- i per cent.
If tihe sooty ivII forsn' aI coal lil_ on the U 1|per half f the orantre,
the rind Iunderneatl h it mIny remain iIgreen ii"irliteily. I ii1,. the lower
:half of the fl iiI becomes \veil coloredI. The retardation of rinti iii -.
delayiln.,. as it does in soIe case)-s the time when the fruit i' I airket-
alie ani d nlaterily iii,'Tc.i-iri_1 the ,iI'i ii;i:.' of culls-. cau ises ti ili.-r
loss. \\ hiiri is 'Cr\ con -,erv at ively estiniited to rai e fr,'mli 2 to 5 per
crniit of the value of the crop.
It is customary to clean fruit noticeably affected with sootv mold.
The pro of .1tlu111111i1 caues vnilny iechanlllical injuries which !i I',,rd
entiirnct to the spores of the blue mold with its r,.-,iliii il decay.

White tlie-; inmiy be controlled in two ways: (1) By suibjeit 1i11 the
infvltetd plants to the fumles of hydrIoc anic-acid _-.. or (2) y
sprai.vin; with a contact ins-ecticide. Tli. latter niethod only is con-
siderel in this paper anlld has the :il\.iilvlr', of I,1,I-,L conrip;il.;itively
inexpeni-ive and ailaptlledI to grove conditions in IlI'ri'.i.


In s r:iyiviii. an exten-lsion rod. vaar iii._, from S to 10 f,'t in h',rifh.
should be supplied with each line of hiose. the Iiitlh Iltpr.i-liil.- upon111)11
the hei_.lif -if the trees. This rod may I' ain ordi nary bamboo pole
or a :n iiil gail- pipl. Ti Te ft uir is more suitable for this work in
that it is lighter and more easily lndliledI after 1.,i niiiiiig wet.


A cut -off -liuild always be inserted between the extension rod and
the hose. This will enable the operator to cut off the spray at any
tijic. either when going from tree to tree or in order to clean out the
nozzle should it become clogged. If a power -prayer is iiused it is
also necessary to insert a cut-off between the hose and pump. which
would relieve the pressure on the hose in case of a break. A cut-off
inserted at this point also makes it possible for a machine to be fitted
with any number of leads of hose which the work may require.
The hose should be from three-eighths to one-half inch in diameter,
of the very finest quality, and able to withstand such pressure as the
methods of application may require. If a power sprayer is used the
hose should be a good quality 7-ply; with reasonable care this will
stand up for a season under 150 or 170 pounds pressure. If a barrel
pump is used, 4-ply will be sufficient, but even for this the 7-ply is to
be preferred and will be found cheaper in the long run. In our ex-
perimental work leads of hose 50 feet in length have been found more
satisfactory than shorter ones. With long hose both mules and
machine may be kept out of range of the spray. Then, too, when
using two leads of hose it will be possible, if the hose is long, to
progress uninterruptedly on both sides even though there may be a
tree missing in one row or the other. In spraying the larger trees
long hose is essential in order that the sides of the trees away from the
machine may be reached.
To secure satisfactory results the application should be thorough
and with sufficient force to break up the liquid into a fine mist. The
kind of pump to be used should be governed by the size of the grove
and other conditions. A barrel pump will serve every purpose if the
trees are low and only a small amount of spraying is required. For
larger operations a gasoline-power outfit will give better satisfaction.
For Florida such an outfit should be light in weight, with 6-inch tires
and an engine of not less than two and one-half horsepower. To keep
the machinery free from sand the engine should be provided with
canvas curtains.
To obtain satisfactory results it is necessary to have the proper
equipment for applying the insecticide. Much of the prejudice
against spraying for the control of white flies arises from the ineffi-
cient results due to improper equipment.
Since the insects cinureg;ite on the underside of the leaves the
spray should always be directed upward. To ac'i-mplish this one
should use a -trailht nozzle attached to an elluw which makes an
a ingle of approximately 45 dgrive- or. better still, an angle nozzle
which will not get entianglil in the foliage and branches. A nozzle
which emits the spray in the form of a cone having an angle of about
90 dr,.-.s has been found to be very efficient, whereas a flat or solid
stream will not -ivc satisfactory results.

bi'HA. IN'% lit %% IITI FJ Ill IN I II I:|IIA.


In 'prir.li-, fr control of w4iitt fi,. the nietthodl of tapplication
is thile same wiicii ii i either ia barn'l pm lp, or a power outfit.
In apphi',, the spray thIe operator ishouh ,ld III' -r l theli fair side
if tile tree and work around to thIe point i ,4a res-t the nachi rn. '11"
second hIalf of the tree -should I e h:undled in like millner. IfI two
operators Iare at w I Iork on the anie tr ee li, \ shou l 1,,,,l l',. _' ii at tlhe
p)oinlt fart lest from the nmachie aiid proceeid until I.v I] leet.
ih'e spray should be applied to th'e tree in a -'- t'lnatic wt y. The
Te rI 'ior should i I_ in at the base a in i w ork to lie to}l, inrlti ii ,. the
rod aIInoIg the branches so as to spray th(ie center of the tree. The
entire tree Iay IV he thus spray ed in s'ctioIns,. the operators prI I, ii li, ii
alternately fr,,ni the bottoni to the tup ind from the top to the bot-
tom. To prevent kinks from a ppeari :1 'l in thie htos e the operator, in
lioIv ni from tree to tree, should never make a complete turn. In
a'e kinks :aplear they should be immediately taken out bu turinlg
the -pr:,N rod and not by sIlllirig tie hose.


It is important tlihat the insecticide used should kill all the insects
hit 1y the spray. Emulsions of various lev1y mineral oils have
been fUlid1 to i,\, the lxst satisfaction. While petroleum fuel oil,
or "crude oil.' and l- ill.i II. or L,;. oil, will I.'i' 'iudl results, vet
thi' par.illin oils, known also as lu, ri itillg oil-. |lavinu.r a specific
g-avity of front 24 to .,, Baunxe have been found to possess cer-
tain qualities which iiake them superior as bases for an insecticide
aIaiiN't the white flies. The f',ll ,,inr f',riiiil.i has given highly
satisfactory results:
I',,l \1l I I N O. 1.
Wti:ilh..ll soap---------------------------------..--- S |-. .l-. or I all,.n
PNrtiitin oil, 2.1' or 2', Bauni .----------------------------------------- 2 gallons.
LWater.-------------------- - --- -. - -- ---.--- --. 1 ill..

In propi' nili- thle s-tock mixture the soap should Ie plt into a re-
ceptacle of about 5 gallons' ;,:lit il \ and the oil iltold then Ih ,lt' .
verv -lqiviM while the mlixtitre is 1"I i'L vigorously stirred. It is
important that the oil be ;ic.I in small ,i,.ailn ities at lir-i ai1 also
that thie iirg e sufficient to keep tihe oil and -",,ip in tlie f,-rina
of anll emulsio l after each addition of oil. lui- at tirs-t about a
pint of oil .liiild be added to thile soap and tile mixture slti rir'l until
no free oil appears. A- the a:imounit of oil is increased it should
always be stirred or mixed tluriirIly before the next addition is


made. After the required amount of oil ihas been added and after
free oil has ceased to appear on top of the soap, the water is slowly
poured in, about a quart at a time. To determine whether the mix-
ture will form a perfect emulsion add a little of it to soft water, and
if no oil float.-, the mixture is perfect and may be used for spraying.
The presence of floating oil indicates an imperfect mixture and
results from adding the oil too suddenly or from insufficient stir-
ring. This condition may be remedied by the addition of more soap,
which is preferable to throwing awa;y the entire mixture.
For spraying orange trees use 1 gallon of the r-t'ik inixture pre-
pared as just described to 50 gallons of water, or use the entire
amount to make 200 gallons of spray material. This dilution con-
tains approximately 1 per cent of oil, which is the maximum st rength
required for white flies and the purple scale. For three-fourths of
1 per cent of oil add 1 gallon of the stock mixture to 66 galhlins of
water, and to obtain one-half of 1 per cent add 1 gallon of the stock
mixture to 100 gallons of water.
Many alterations may be made in the foreg(oinm forrrmula. The
quantity of soap will depend l:ir-gely upon the time consumed in
adding the oil and the amount of stiirinL- accompanying this process.
The amount of soap is lessened if the stirring is uniform and if
ample time is taken in the preparation. Petroleum fuel oil, or
"crude oil," and distillate, or ga.s oil, may be used instead of the
paraffin oil, but in these cases a mixture of about twice the strength
will be needed to kill the insects. The amount of water is unim-
portant, since the emulsion should be perfect if either 1 or 4 quarts
be added. The only thing to be remembered is that the diluted spray
should contain the required percentage of oil.
The following formula from Farmers' Bulletin No. 172, page 17,
has also been found satisfactory:

Water (boiling) ----------------------------------------------- gallons- 5
Iistl:t. Baum6 ------------------------------------------- do-- 5
Whale-oil soap -----------------------------------------------pouuds- 1J


Dissolve the soap in hot water and add the ,litillate. thoroughly
eniul-'ifyin by means of a pump until a rather heavy creamy-
yellowish emulsion is produced. For use against the white fly dilute
1 part of the stock emulsion with 2., parts of water. This dilution
will contain about 2 per cent of the oil.
'IThe term distillate is commonly given in California to a form of petroleum widely
used for spraying purposes.

PRO4l'i Br \tV INSE4TIC iDS.

There are several articles on t ile marketI unIder the lit ::il i f lmiscible
oils which when properly applied will g.i % sIat is'Ifact I rv-ul t.
'lht-4'. however, should not contain sulphuric .'id, rwin oil, or
cirb- lii acid.

So far as the Ift.t of various insecticides on the tree- and fruit
is concernIed it is safe to spray at iny season of the year except dur-
ing the lhioining period. If the :;ippli'.ition i miadie di'I iii-, the
winter, it will be fi,1111i1 much more cionvenienlt to spray allirl, the
removal of the fruit. The insecticide will do ino) ilijuiry to the fruit
itself, but its pre-lnce on uinwailied fruit tmay prove 1, i,., ti iuii 1 .lle
to the .,ii-nuiilTV. It can also be .,jlid, I, i .IL tle lsummllllier (i rainy
seli"Ion. but :I Iri I. i vir\ f;i ll, or winter alppl ications are preferable
in that the beneficial parasitic fniii..i are nolt affected 1,\ the insecti-
(ide durir,,, these seasons.
So far as the effect on the various 4I ip,-, of the insect is con-
cerned splrayiuii, may be done at any time. The white fly is in the
tenderest larval :,i,'.- about two weeks after the disalppearan1ce of
the adults of the first 1ir,,id. and if spri nir, is done at this period
the insecticide can be used at about one-half or three-fourths the
u-ual strength.
Thie gitrer should aim to keep the white fly below the point
where it will do serious da.imi r, and the number of treatmilents will
depenlid upon the he iit I Il lrii.- of the work and the abundance of the
insects in the gii', at the time of spraying. One li,-,,inln .prayv-
ing is much more .lh.,liive than two or three carelessly applied.
The ,iipl1i',ti, n of the insecticide should be so timed as to be 1 l..-
tive in killilig the rust mite (A'r; i ,/,', o,/ ivorus Aslim.) and scale
insects as well as thle white fiN,.. Experience has shown that two
'[)rw in^ry l,- are -'iili i,.i! to control thle white flis-. One of these can
be ,ivvcn in the -jiiiLn,, foll,," iiiz, it I, an i irl"v fall ;Hi()'[ii ri.ti .
or one can be ,ivM.l cluingg miiil- iiniui. and the second luringg tlhe
winter months. The I-ri,-i' allnd summer -I3r.u.v- are also beneficial
in killing,, the rust mite. Scale insects frequently :Iii w such a foot-
hold as to demand winter tr,..(iiI-iIl. but in some instances one spray-
ing a year liai. prllii,'., clean fruit.


The paraffin-nil emulsion .-liray when u-md with 1 per cent of
oil will kill the rust mite and its eggs and also the purple scale
(Le'pidmpht's beckii Newm.). It is also effective when used

b i'I.R N [ 'O r c it i ll III1 I I. S i i lj slINl.\.


against the young of the Florida red or "nail-head" scale (Chry-
somphalus aonituin L.).


Thie experiments so far conducted indicate that the oil sprays do
not possess any fungicid(lal properties, nor do they affect the bene-
ficial parasitic fungi in the least. Tlie-e fungi develop during the
raiiny seai.ton, while the scale ini-cts. rust mite, and white flies do
their greatest drainage from September 1 to June 1. The fact that
these sprays are applied during seasons when the fungi are inactive
is evidence in favor of such remedies in that the increase of the
fungi is not directly affected.
Secretary of Agriculture.
WASHINGTON, D. C., January 18, 1913.

\DDI TI'N.\ L, COPIES of this puIhlication
may be procured from the &-'PEErNrTEND-
ENT OF DocuELTrs. Government Printing
,Office, Wa-h mbingon, D. C., at 5 cents per copy


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