Citation
The red spider on cotton (Tetranychus bimaculatus Harvey)

Material Information

Title:
The red spider on cotton (Tetranychus bimaculatus Harvey)
Creator:
McGregor, E. A
Place of Publication:
Washington, D.C.
Publisher:
U.S. G.P.O.
Publication Date:
Language:
English

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Source Institution:
University of Florida
Rights Management:
This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
Resource Identifier:
29684495 ( ALEPH )
28102209 ( OCLC )

Full Text
7 I3 I I -


U. S. I-PI'.\RIT1I ENT OF A(\RII'I.I NE,
BUREAU OF EI i ,ILiY--r iIHI' LAR N 172.
L 0. HOA AR I nm ....i.. *nd ( h Au.




TI!; RED SPIDER OX COTTON.



BY
bly

V. A. M I l In.
I ,,t .. .. | i 1. s a t.


I
~




I-,






















B'Il fi\ UOF EYTO lIOLOOY.


L. 0. HOWARD. Et,,l'eini,,gi.,l and f'hief of Itureau.
C. L. MARLATT, Eiii,,ii,,liif and Acting P'li f in .I b.%,iie of Chief.
R. S. CLIFTON, Executive Assistant.
W. F. TASTET. ('irf ihl.'i .

F. H. CHITTENDEN, in charge of truck crop and stored product insect investigations.
A. D. IOPKKiNS. in charge of forest insect in r, ligations.
W. D. HUNTER, in 'liriiq' of southern fili crop insect iir< itigtition .
F. M. \Wr: s I ,t. in r hai /1 of cereal and forage insect investigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILLIPS, in charge of bee culture.
D. M. ROGERS, in r'itirn' of preventing spread of moths, fi ROLLA P. CURRIE, in t hi'!1 of editorial wiorl,.
MABEL COLCORD, in charge of libirity.

SOUTHERN FIELD ('ROP INSECT INVESTIGATIONS.

W. D. HUNTER, in charge.

W. D. PIERCE, G. D. SMITH, J. D. MITCHELL, HARRY PINKvS, B. II. COAD, R. V.
MORELAND. A. W. J. POMEROY, uigagii d in cotton-boll icecvil iire',titrin.%.
F. C. BISHOP, A. H. JENNINGS, II. P. WOOD, W. V. KING, ,iggif ii in tick life-
history investigations.
A. C. MORGAN, G. A. RUNNER, S. E. CIL'MB. D. C. PARMAN, i tgir idI in ,,biro
insect investigations.
T. E. HOLLOWAY, E. R. BARBER, engaged in sugar-cane insect in r, 6i#a1lioi,%
E. A. MCGREGOR, W. A. THOMAS, engaged in red spider and other cotton insect
investigations.
J. L. WEBB, i engaged in rice insect inrv.'ligi lioii..
R. A. COOLEY, D. L. VAN DINE, A. F. CONRADI, collaborators.
II






DDITIONAL COPIES of 0h13 publication
may be procured from the S LPERrNTEND-
ENT OF DOCUMENTS, GovernmentI Printing
Office, Washington, D C al 5 cents per copy

















CIRCULAR No. 1 72. 1-,-u'- M I 7, V$.

United States Department of Agriculture,
BUREAU OF ENTOMOLOGY
L. 0. HOWARD, Entomologist and Chief of Bureau.


THE IREDI SPIDER ON COTTON.,
( If f. Ini u, ts bimitn 'uhittls I Harvey.)

I!Y E. A. Mit ,.o .
!ntoiwologiei ll Aitant.

INTRODI) (TION.

The minute reddish mite commonly known as the red -pider appar-
en llv is 1,eonin n of the serious n of the (o ee of lthe cotton plant in
thn, I'n ii, StatuI- It is now prevalent tlhrl- 'I.llilil tle ('otton belt,
1nI. epqlti.llly in the last few seasonl-, haIs a used milucli ala irm :1, Ill'._
the f.ir lr',' in certain sections. Seasons of excessive *1rnil t are
faioraldh to the dvlop,11vioi if the mite. and ait such tines thle pest
i1icrea.. o rapidly th thtthe ,l i.u.'i often becomes severe before its
pt,,.e'lI'e is 'l,,t ctetl.
Ied-' i-ipler infestation is frequently miscalled "rust" by farmers.
since iife-tei, leaves soon turn deep red on their upper surface. Si',1i
leavvts, however, if examined iiieriir;iil i. reveal the pre-ewnce of tlhe
red -piler-. and l ]w inconslpicuous wes behind which they are f,''I-
int and laYini their ,.'..-.

HIST(RY AND "STHITRIUTON.

Wi1l\ the exception of an outbreak in Louisiana, reported hv Prof.
II. .A. Mir-,.:,;in in 1:':. sevev occurrence 4f the red spider on (Irotto(
1i,.d not Ylen rI.,,,rt,.l until 1'.I:. at which time ii, plliiii- of daim-
;ae came f:1 ',rii Siali Carolina and l,',ri.i. In 1!'1 Mr. V.E. (.
SThik. ir. ill r i- ba d prinmarily u 1on work doe at l1atcbur1 S C'., In 11 .11 and 1 2.
under th-. lir, ii.i of Mr w. I. Huntr. but also Includ.' thb. r wults ,t obsrvatlona y
Mssr. A. A. Runner and II. F Wivon during the two prt'%ing va of and supe 'r1'ew ( ircular No. 150.
1






THE RED SPIDER ON COI TON.


'ilii-. then of this bine.iii. found severe infestation in fields about
Balt,-hlilr. S. C., and the follo iing year he rep,,irted severe injury
in North Carolina, South Carolina, GeoLria. and Alabama. Since
then the additional records of Dr. F. H. Chittenden and Mesrs.
G. P. Weldon. D. T. Fullaway, and others, as well as the writer.
have established the presence of this red spider from Maine to Flor-
ida and westward to C:alifiorniia and in the Hawaiian Islands. Witlh
the exception of western Colorado and portions of California no
complaints of an ;ii riinig nature regarding this pest have come to
the writer's attention other than from
'' ,ff the southeastern portion of the cotton
belt. It is here that the red spider ap-
,,, jilt ,' pears to have found the conditions most

\~ 1The red spider was described by Har-
X *V in ls!):, as Tetranychkms 2-,,n,,lat,,.
Harvey considered it quite distinct from
the European species T. telariws L. Ilis
types were from Orono. Me. In 1907
'- Prof. H. A. Morgan published observa-
\tions on the cotton mite, and ipparently
/ .\ :wi'-pU'l the determination of the species
/ / \ \ as T. telarius. In 1900 Mr. N.'till Bainks
/ 1/ ( described the cotton mite under a dis-
I \/ ^LV~ tinct name-Tl trI., 1u,,,. I /1,,' Y--bit
S \ y \from the study of additional pecinmens
has now concluded that the name is
i / synonymous with Harvev'\ T. 1Unai-u-
latus. Specimens of red spiders on cotton
from South Carolina have tLil)on two re-
Fit;. 1.-The redspider, Tctrany-
thus bimaculatum: Adult fe- cent occasions been (determiiK'd by Prof.
male. G r eat l y enlarged. A. Berlese as the continental species-
(From Banks.) #//!11h iTt i "., telarius. As there nems to

be. consideral)le doubt on this point, we shall follow Mr. Banks
IIi (onsi(dering the form with which we are dealing as T< ,,iii,,v fiu.
bimniaceidatis.
DESCRIPTION.
The typical female (fig. 1) is 0.50 mm. long 1y iv I mm. wide.
broad-oval, widest in front, and the leg- are shorter than the body.
Its color is usually brick-red. The typical male is 0._'7 mm. lorir by
0.15 11mm. wide, oval-welg ihpe. naITowed behind, the t1eg?. a.*iout
,.,iting- the length of the body, and its color is usually reddllish
amber. Individuals of both sexes usually possess on either side of
the body (l dark spot, caused by the food contents. This spot 1i:%i
vary greatly il color, size, and outline. Similarly, lepiniilng upon









tHi hows p la!ll ni"l til[ l1 1ity. Owe '_, i w. 1 olor 1d ll r Iid pirl
Ti t -. _.- -li f I( ,i, i. *, i it i i- f ii n, i :i it t \ N til ll.
d il' t i yy. ainer %., iit' r Imi t in Al r1q trt l" oH M II te HIM e arclA




N\l 1b utI -U.s F.01 aI I t I I I H~ Ia h I. W 1 -- ~ l a" l
lrL' Th.x are I" i t lh rI d ,i,, tii| 'lw I irst laid ar ;i.. Il \ear ai,
Water.+ i.,,ch fe~,male lalv i~n the monrth- of Jlune.+ July. and11+\,.., .nL ii i

iibaint .','I tW It,_._-' !llle .,i h el r Hfrod-t Ia ll Vtin ) Iat- xIIced, I '",
I'imn lly :a bonitr t hl '_t-' f ir t dhlox +t,:c l|Mr ,la I l''r ;i I p riod of 9I or lti

d(n.\ in sii ir'r \w thtl + r. [Durit ti)' w do iriimir iwootlh- tIhn ._,'- Ih tcli
Ini a oiit Idljy t'l. r l.,.ii l_..- i i, .
'I ,.ll- n l + itchrul rl ,l liAh'i. -,II, ilk"! ll irvN\ ;ilIHiovt ronm l.
Il s ix :1,. 1. a l is i~I\rly U'olorhW -. It !" aifs f ,,li,.,_, !t ,liK :iiPl
till sllmimiilcr tiime) 1ift*1 l t(\%I- dIN\ N q* a tiv, il\v it IN1,- liH on icl. i i i' l i+
ij ('(]l +, cil t it< ,kin for theI llnI tinn'. ;I l I ,I _, .1 ;1-i Ilf, |)i'i iiNiry
iix\iili, with :in l addlt'td 1' 'ir of l'._- ili kii ij ei lit.
TI'w' priiary iyuNph ILt oitM'lm li 1_' in sii 21tI Aii ilrklur in color.
but Ti,.-~ no inliclation of -ex. +t'di''' toniitiniuitd ;Ones ivx l. iitl at Ithe
Itwminin m of id not licr two-day l"'ii,,,l (in tirinnnwr nimildish ai m'cont
ni,,oll ii,,.' i 't'il-, \ lhitch ,ives' rive to thlt thiril -t i, tll, ,' n iiinrv

'* il I thin t n i- lii al vi ,,in tlII ilt ind1 i iiIii ofl sex appexwi lrs.
- witht tihe I', 'l ." -a i!iii tw lxx i nsn i lail x -ill. itn i\i i- l inlr
fir the ilt, coni lt tioin of tili, peri"ld. ;it til t', lnd l If wlihicl tii tilt'
-kin is -lietd f..r tlilt third tiliime anlI :1it a1-t ti l rfcllt, dcx,,Oljei d
;ilill m itt's .1i1p1 .ir. A t tlt 'ictir citi- of eai'i itilt the -kini -lli s in
two cro;wi le, aid thle e' illture cawlt x- out ofl if til wo tax litNl\-. Their
old tiIt skin, are t allv to i :eli i :illlle seen in I nda l ,ii li,'' thle lili i1]-
.rf lith web.
I IlE ADULT M\AIA Nl I Ix \IATI, floMi'\irA I)>.
CI ',, ri,' iii,' tihe relative ihltiitdint' of f a Iile i a lit iliiais- it mIlalV le
iti thliat tll're iet )ii' to lie a pr 'tolm 1inalice of fvitiNlt- tllii..j'..',il
tIhe ltililller., hIit to\\w rd lite apitlachl ot coit l weatl.-' the .olcirrlice
,., t1ile 4 xt. lbecoles more elel'II et ionl. iIlie, IL'rid TO if hilflt f lie
ndit it t'- ill ilh vaiie fNirim 17IT d y it ider to- -,+eve1 l \i ntllti>h-
in wil iter. Tle male i- lIorte' r li l. As I, tlre i-tatetl. tli' feiiile
is< de'idedlly liIli 1t'ita" till nih il/ mo ei ro ded I li'l. andIi o)f I
muh epe olr1Si does not Ili') a0o, 110uchll, a1 nd \\ 111i -111,
doiti'h her iotionO i-. at e h low.' iill 11e, 1 ti- i er hain l. wn iti ot l 11 atM 1'
tht' itile i- freque'tilx -t-en 111." i1;,' ra[HidKi' about I I, l -I ani
I,.- :- l l- wI I ll Ie-,'-t illi I r i Is t'I ii thi a tI, t- ,liI-' x \hl1t lilort coul-
[,i ,io, i ii I heI it aeI thiIai i the I' .l. -t'. it addI ition ii, Ilie I f tof
th< aihe i are WIt r inI piiop-irtlon toi It -li d thlii ;Ile tlio 1e 4f thle
female. The I,.- *t ie tihr.-t r l, r i'are e"-|eciall 1-'-I in tliet lil1 aind
iare tontl tlt'"- adapted for .li-,'ii",. I I,. exet -. coil -i-,' tli o if tI W
orbll oiie clo-e 1-liin thie oiliert, inre -itnited ine r tlie '1iii .1
the i lt, J directly ov er the -et-olitl pair of 1..'.,


TIHII IWhO 1I'IllI fix tCOTTON.








THE RED SPIDER ON COTTON.


MATING.

Almost immediately upon 1ecomining adult. thie re id spiders nimte
and begin egg laying. ThII males -,eeni to recogii-ize unfertilized
females with ease. 'lThe first egg, are freq Ini1l deposited on the
same day upon which the transformt;t ion ocur_- from the last
nymphal to the adult -rage.

PARTIHENOGEN FIS.

Experiments conducted with unmatcd fimiale reId pider- clearly
prove that they are normally capable of lviN g eggs. which in turn
hatch and develop into mature individa la-. N,1 tle.t.-. however, have
been successfully conducted to determi ne tlit. -exiial fertility of the
latter.
GENERATIONS.

Tn't season of 1911 at Batesburg, S. (.'.. w;i- Onie ,f iiimiuiial drought
and heat, and there were about 17 genera tioni Ibetween March 11 and
November 5. The time required for a r.iil, e gelIeration varied from
35 days in March and early April to 10 day, tihroighouit most of
June, July, and August. and to 25 il;iy-, ini the greater portion of
October and early November. During thli -aime period of 1912 at
Batesburg only 16 generations were iprodiiu(cedl. The 1912 season
was late in commencing, was somewhat ,ooler thian that of 1911. and
more showers occurred. From April 2'4 to September 25 there was
small variation in the time required fir tihe generations-averaging
about 11 days. Two generations developed each in 9 days. which is
less than was required for any brood in 1I'll1. Thirty days was re-
quired for the October-November generation. TIhe following table
presents the duration of each stage of eali .)f the 17 generations
for 1911:

TABLE I.-- D', l,,iii# 1it of generations of II, I /I /l( i -r ,in r'o lFl in 1911.


Period covered by ,Pnerai m un



M.ir 11I1.) \pr I1
,r i I-, [r. -.iV
\[,r. I v M i 1 i..
M~iy 11 11,: M iy 1' .
\1 U LLO J U l -e t. ..... ...... .......... ..
Itine 7 to June 17 ..............
June 18 to June 27 .....................
June 28 to July 7.............. .....
July 8 to July 18...7.......................
July 8 to July 18-..... ......
July 19 to July 28......... .................
July 29 to Aug. 7............ ............
Aug. 8 to Aug. 17..... ..............
Aug. 18 to \% i'! 29.......... ....... ....
iI- 30 to -'l'i 9 .. .....................
", l|. l0 to Sept.24.........................
- io 25to Oct. 10 ......................
Oct. 11 to N ov. 4 .......................


lnruran-
I ir' il
per iu,


I~p1


l.arval N% mph
eill
[flOl'per io1.


Iy.. Dnir. ,
1, I

. "
4
4 -.
I 2
-2
", .
i.-.


Dijy."

3
,)
2


2
2
.1


2
29


A average.


Nymph Onipo-
S2 1 silion to
period adJult.

Days. Days.
7 35
31 15
2 14
2 12
2 12
2 11
2 10
2 O10
2 i1
2 10
2 10
2 M0
5 12
2 11
1 15
1 16
5 _25
2 14


"lcrier
ation.



2 ......
4 .... .



9.
10o
1L ......
12
13 ......
14.
13 ......
15 .....
17. -







THE 1:1 I1 S1 11,1 1: ON (*(>TTO'. 5

Talel II indicalties Ill, duration of. am! tlike p., ,il ,r, red Iny, each
.I the 10 ,. ,. li*f ,r I '.' 1,W ell a for tih 1911 1.2 \w ilt'. i I[,,_
..*I ,,- :,il ion.





I Jtl.K ne I IJ- ) o \it "I I )r r l if l il l 2 In ill \IA I 1
I .......1., I ; \ 'l,y w ,,, 1 2^ II *. ) ,,.i, lt ,... .- ., I ;^
w, .' I" In


V .... l >,l O t o A pr. 21 .... 1 1 1 1 U.l ", :l In I' 11 .. .. 1
2 ..... U r 2tin .. ^J *y; >. .. .. 2 I 7U ,, '.1: t2 o AUK. t .. . ... 10
r. %" I M If A n f "0 . . 1-1. *:o t '* id'. v on tw o in 1. 9 I I




.... Iii t to Al, 192 II


Flthi iT thi' wiut.'ring roner tion *i Il sho d rdM til l *iitc, l hi|b Ibic Irll d..

BIFTIIT>II IN OF WEAT11ElR Ii TI BHEEIt IN- ; AC TI IVITIES.

Ti'11 iiil'ln i,'u' olf tih' weatlher oil 1 li -,li,_ ;irttvit\ i very notice-
able. Hlot, dry conditions ,rii.ill\v faivor miiid ha:iiten development,
l Ilh c(xl, wet weather eore-.';l,,,ia1iti'l\ retaird- it. A feinale Ila iti]
1,i1 nhi;iell1 about h or 7 ,'-~ per aiiv will often iipon tIe occurreci'
,,f a very hot dh:iv suhddeinl increase the itiinlder to 1., or ev en iiore
S'- per day. or upon a chilly dnv mhy driii 2 iiddenly to 1 or 2
<-t. ....It is easy then to 'iiiler-iiTi.| lhe retiinrkahle r .te at which
thi* pt~t inceieaset ,luiii'ii,.. tinies of uinsi lial Irnii-,Iit.

SIII E(VATIIlNh ON IIA lITr.

In ,-ilhili-laiiti, herself Iponi (ottoni tie feiiale selects a concave
T hrea 1tw'ieeii the uldlelr veillns of the leaf ai ii 'lli ,-ii at once to deposit
i' .,_'- 'ii.,-e inaiy he attached to thle fibrils ,if tle web -lightly above
ili surface, or. a. as seeis Iost ,fi,'i the icase. fliar aare ptlaced directly

iupon the leaf. The ,L.','- are usually clhitered rather closeelv and
1.1 rely occupy an area Ireater in ize than that of ai dime. Fr t'll I IL,
,oltinies interruptedly llar,' -,L ,,'l''' the lii ii"t of ,,_,j haviri,., and the
" 1.11.i1V area ,f the leaf Mt'OTiier thickly dotted with Ilie blackislh-
WlIrl ipnture ; &. a'ks. Meanwhile a wiAi -r,, spot hlias aainU:ired tn
t Ii- g 1 Iti surface of the leaf directly over thie \'ii'b colony, which
"r n il- as the colony inclreases and mav finally color the entire leaf.
As it, l,. .- hatch the larva remain close to tle place of their hib'th.
Ilt liniite seem to be decidedly ,.ri,',arioun. In ai Illiii colony
Here i- usualiv litih, web u'p'iiindI. luit where thle plidets ari very
:aiundant the web nimay become e ,i(it. c',,-I lie.a-. It ilil, less
ii',ii' s1om. ITe protet'tion friom adlv 'here we er edition l. al, well as
i ..4li-i ihostile lintrudeIs. since l upo In sev eral aoccaioniis- pro lcdaceolis






T1IF RED SI'IDEi ON COTTON.


insects have been observed ensnared and dead aiiinilig the fiber.-. New
f.lo:1h.. after imitini. either select an attractive 'pot on tile leaf,
or migrate upwardI to a more I ei1)pti iig leaf, ,ir. as frellueintly i- thie
case when o,\ i', hd,,. travel to another plant.

TIHIE VIOLET AND) POKEWEEI) AS HOSTS.

1When cotton (dies or l)ecomnes .iiiiijit|iii,. in the l:ilc fall an exoili-;
of red spiders from the cotton fields occurs in the effort to tiil nm ire
.Suitable food plants. At this time cotton mites may be can-ily foulid
on a number of native and cultivated plants, prominent alnmo, wlhich
are cowpeas. tomato, Jainestown weed, ironweed, pliew\veedil. and cuil-
tivated violets. M, i- of these plants die after the fro't-. blut ponke-


weed fiiurnishes considerable










:.. 0 0 0 0 0
0000 >
'.'*.' ,,.* -0 0 '. *"
.* 0 + .* *


00
0
-* a '"'*


FIG. 2.-Diagram showing how vio-
lets growing in .I'r.d i give
rise to red-spider infestation In
adjoining field. The infestation
is most severe n-air the' yard.
This diagram is typical of many
cases found during, 1911. (Au-
thor's illustration.)


green tissue beneath the groUi',id level.
and the violet remains omeewhat green
liir'oiighliit the winter. Out (if mianyi
cases of cotton infestation inve-.igated
diliiiiiig the last two seasons tlie l -;itI
niajority of them have inidicatedl
most clearly that the original -ouirce
of the pest was either lthe English
violet (figs. 2, 3) or pokeweed ( P:i toi-
/ Practically all occurrTences in urban
localities have been intimately a -soci-
ated with cultivated violet phlant- and
doubtless origi iatel from them. (_)i the
other hand. with very few excepitiotni
rural cases of infestation are traceable
to pokeweed stalks growing at the
field borders or on the terrace-;. The
description of a rural occurrence at


All"1luilc. S. C.. will serve to illustrate a typical case of ,ri'iii from
pokeweed. In this instance tile infestation was seen to grow i' 'creas-
ingly severe as one approached a certain point on a terrarc. ('iin-
xciriing from all directions toward this center, infestation cleairlv
b)ecamie heavier utintil an area was reached where the plants wei'v iv-
inuded of foli:i,2,. Precisely in the center of this area there grew a
L.ir_'e pokeweed stalk. It was "alive with mites and wa lif-litl]
festooned with their X\ e01 di1.
It is not yet entirely clear in what manner the red spider pa-ses
the winter on 1)okeweed. The plant is a perennial, and the s-tilk- die
to the ground in the late fall. Just below the soil surface. limwever.
the soft flesh roots, which are succulent. 1 c-_ii (figr. 4). In a:ilddition.
at the crown of the root. at about the ,r,-niiidl level, there are :ilwai-






1 he1 ltlF:l 1I'lUKIS I ic tItT X III7

In be found 1l iiliL.'t tlihr w\iliter Iiitiithsil tn' tender dormiliaiig t uld-
\.hidi L'i',' rist 1- the staklk. of the i ii'' ,,11, wtot. I'loni \NoemH
ber '2.': I'l followiih\ '.I -rr l .'- ri'r frot4 st Bai tit ii rg, S. ('. ;i
frv\ of thtie litn c lr- et, ii|n |iirmm lI\ f, ,ii i n' onl thi .' \ inter T,1iV,.



A 1 iel lit of the illi\e-tl.' iii ll I ii.. l e i -'. iL. ll1 e'r N i li tlt.
,';irlil o elrvili(ont of ihe red -1i.Ylr o)i et iii. lti- iiiite it.- Itei
'mii ilpon ovter '.ill c'iei of lihilil i ir, t1,.ii,... Ti 1tV. o zirliili'utiil
]plililt-'. iii -,:ll',iiai !lin l iI.I .rof)i I l l iioi(t< otf tIi>t lilt |x1 4I lifil
,Ill (easioinlilv eiecti ~e'en. Iit it lih- lien foliud comiioinly thl ._'li-




















I'rl. 3.- 'i[ 'i d 411 1iir :1-irr -in pKI ts '.-w ii 11 i n -.i i-l 'f u s p i'i il
l'i.B .' w I'1. Bfi v tol~lr tir~ll 1i?(1w |)ilt rumll Ulrielnsl. tl 13 I h s l ll"


o01t tihe a1tivf fia- lon tiu on tlie folho i,. I ,.iit~: 11 K i1i. m I> It"[' t1.
4:ilii i ironIIveil. J, I'jialem-oI ak \\ i, Jiinie-town wNeed. kr:i. ilto iti.
wild blackberry. wild _i,, .i.iiiiii,. l)kewti. aind iitl.,li.li viholt. At
r', ii ,-\ ille. S. ('., .\ilnii-I ". Hiu1 ;i casle Wilv s '-en "here ;i li,.I.I of
corn was immediately adjacent to a I,.,,1.ly infeted I cotton iatclh. T,.
iiifre-rili',li li1iil l-pread into thne lorn iil tlhe cowipea-. 'I"\^.._' lt{,-
tween the corni rows. One-fourth of the corn hall hfei pullet I tip
,,ilI the balance was very severely inf,.-,.'',I Matili of thle corn-tailk-
,'\lil~it ,,I l:il'_,* rus-t-yellow l)lottclhes on their thladtle. and. it fiact.
ha the pest ipe,.irei', when the corn wav voVuIIt er it prohahly ax w1mdl1
have ruined thle (oip. ()n th(e cowpeas the ini',-li.iti ou w~i- Iie uiv\.
iitiliiV f ithe leaves had dropped, and those r> ii.uiiii..L\' waere ,i,-'clored
.i l1 ,li- ,rle .1.
T'-n;': 1 -l7- 1 ; --







THIE REU SPIDEII ON COTTON.


IIIISERNATI(ON VRSEi'S WVINTERIN(G.

Some observers have liliil,-iit that the r, I spider ci',nounin'i] hiber-
nates in trash or in tile soil in cotton W.il-. but thile in-e-tig;ttion ill
South Carolina have produced absoluteIly no evidence to support tltii
idea. I)uriiLi_ the late fall and early -p'iiigi. when the weather w.i.


F1I,;. 4. System of fleshy roots of the pokeweed (Ph hjtob icca dieeindra). showing iTi
intl rctive winter bIds nit about the ground level. !is indicated by the dotted in'.
I )ri.inal .

as cold as it becomes in Soumith Carolina. trash lhas been taken .'everal
times from fields in which the infestation had previously been severe
and examined with great care. A few minute dormant acarids and
other forms have thus been o ,itained, but no red -pider,- have been
found in such material.









"l' ii I |I' IIi-t IIi i f I orc -1 A- 1 11ctive t h I II,,LIl,,,' tifi w illcr
livl can W Ju hi uld. Mr. (i. RHllTu f0011 0 icli 0 c ialult" ;At
I ila -l .I. ii Ir S. 10i louicn ;r *2 1'.,"1. M r. It. F. W\ il m >b ervf l
ml., spidlei' f,.,.li,,,iiL e carly Icln'nnry sit lth samen h x'nlily. '1'1.c w\rih+'r


late a, I)ecen wr 19 at I',. l I.H: ,I i t 1 ii mc h-li -t iI 1911. Adhl-t
weii he 1 a live on vf il ts ;i' t I: t -'i ,"i Wlih AI! -Vy _' ; 1'9 '2. f 111.r the I olI 't winter thct co Iti hiid \ IXI Irf1mv on fnr tIi my \ mc -.


I'i;, 3 n nfl f tctd cotton plant. Growing In saunn thld as show' x in I *. i
ll'r+y jl the lo lIrrl iu f if.tti tn b t< rMd sItha hl+r. i& ) ortidi.

Tli liit n .ii i1 I the actir re1l -|llh .' 4 'ii'ri' i the 1'<> l -l t w ti, lr i-




How do red lipl irs I )e'Vfmi e-t"lilihed upei olt In cutlout Tlevy liaxve
to win.o and their bI,--- ;re very minute. ('lost ohervationi reveal
tli it on the H ',>in t, thl v normally travel it the rate ,,f 1 indli 1,
15 I '*rinl:. which, if hid intained. woull total 1r-1 feet in 24 hi ni .
Rid spiders are doubt le-- ,wca-ionall tranus-ferrt'Id I- ",,-. lii'kvi-.


'ri ti tt l> W I I! tN' 1 4, i( \ .






TIIl. RED SPIDELE ON COTl'TON.


other domestic animial-. insects, and birds. Strng winds inmay serve
occasionally to transfer them from plant to plant. It is the writer'.
firm l1 .lief. however, that the chief means of dispersion is the red
spider's own ,florts. W\lieni once established in a field they mayN be
further distributed by farm hands and by stock while cultivation is
being carried on. They also spread from plant to plant along the
intei lahing branches, but traps specially prepared with tanglefoot
andl( placed in the field have proven that indiv iduals co i uinonly crawl
from plant to plant by way of the stalk and the ground.
Since the red spider apparent' ly uses no instinct or intelligence in
finding cotton plants, it follows that the pest must lit upon the cotton
stalks entirely by chance. Tie result of this haphazard manner of
migration must necessarily result often in the penetration of the
spiders far into the center of field-, thus giving rise to thie mistaken
impression that they had hibernated at these point,.
Furthermore, as the likeliholod of the discove-ry of cotton by the
spider is doubtless in proportion to the thickness of the stand," it
should follow that the thlick broadcasting of a narrow border strip
aml,. the eg],, of a field adjoining a source of infestation would serve
as a trap crop to intercept the majority of migrating -piders. This
strip should be plowed in as soon as there seems to be danger of a
general movement to the main field. (For a practical test of this idea,
see under Prevention, p. 17.)
There is an old adage which has come to the writer's attention
several times the past season from the lips of old planter-.: '" When
thIe pokeweed turns red, look out for the cotton "rust."' This ex-
pressi on. said to have been enimp)loyed in antebellum days. i-. of con-
siderable interest, since it contributes evidence tending to prove the
long existence of the cotton mite in the South. as well as the function
of the pokeweed.

TIME OF APPEARANCE AND DISAPPEARANCE.

In 1911 the work of the pest (n cotton first became noticeable about
June 1 at Batesburg. The past season (1912), however, red-spider
work was not evident on cotton until about the last of June at that
locality. From the answers to a large number of inquiries sent to
farmers throughout South Carolina, the average time of first appear-
ance in fields the past season is found to have been June 30. The lower
(sandy) section of the State averages one-half month earlier in the
pest's arrival than does the upper (clay) section-June 2.-1 marking
the arrival time for the former and July 10 for the latter. Although
lhe pest does not become readily noticeable on cotton until some time
in Jimne. it really establishes itself considerably earlier. Mites have
oCCasiainally been seen by the 1st of Mayv on -eedling pl:1n1t, not Over






'I Fit IE s IPI'tPISI O 0 S COTTON.


Sinch s Ildln. Ill bWth .1011 ;lU l 110i2 tip, ( q Allminlm d C( mttim
alhlM t Ithe h:11t -4f A1-- ,,-t. Tliis Usk"W Iln. |" itn l ,f ;activity ro"V
aiml lN; 1- WCels.
N \lTl KrE HI' D\It.\UI-:.

'I l 1. (l kCienc I of t i I l tl f< c )(lttili i i In -I rv cih'l Iv tIe -IHI-I
eIt I !tl thn. '| "V silrfsn t.,of (I1 lt;f ,f 1i 11l( lr( 1l | I..,.,.,. iL.IIK iIfc- l l il y rfi|

Vvi.; (}.-*, Cvwn section of nlormal rutt lv Ifi; h. rrin-v setiont "I c +tton lral" injm''"tl b3
tr rfi a'pId'r. TI', pIun 1I nI ,r I'. r i ''n r. \I i- ninc tfI' dT
t ttor 1:u 1 tratton. m

,li-lrteil. and drop). FiLi,. 5 lows an uiinfstet'd rotto( n ( 1lant for
eomparison with lii.'ir, 7. infe-'ted. The lower leaves nuially aire first
attacked, but infestat ion slpread 11pwa:nil until often only tlwe bare
stalk anid one or two terminal leaves rentlinll. (ee lii.'. ) Sucli
plants almost inv ariably die. T1i. injury to the leaf a:1d the di-
coloration which fllws the f 4litn of the mites aire easily under-
stood by re fer'rilI, to tiLu' ,r 0. whici represents ("i) the appearance
oft healthy cotton lea f-tissues and /) tihe' condition of the ti-sue
fitl. t',elilg by thie t s et. AV ireviousIy intiateld. thle worst spot
of irfirt.mlbi,, are either to he found in cl.se proximity to yanld witi
Irdhe- of violets or to a ,lAmiuu .f pokeweed stalks. LarIO'e field-s ar'
Iriil lvy never m,., ll,.h ly d i, dtetl. hut smaller iI, fn ', ii, : lv
ilt" ,1i, 1 wholly affected. A tI,' I'-mlii exa inflation of ill t ichdil within
1 mile of the center of l'es' ille. S. ('.. was made w ith a view ,f deter-
Ililinli. the exact status ruf reud-->li'li iinf,- itiot it oI ne p' ci ii.








THE i(iE $l'IDEi ON C*l'l TON.


locality. In all, 99 fields were examined as carefully as po-ille.
The foll,,\i-l_, table presents the re.-It :

T'IABLE IIlI.-ResiUtlts of an ivc Icstigation to determine the dil/ of if iifrxtlu#,o (,f
c i(,tto byit the re'd < ,i, it I. ill,. S. C., 1i!12.


I r-l .' i = iII i l l ,. .I


Very acute...........
Verv considerable....
Slipht ... ....... ....
None .................
Total .......

Total number of fields visited .........................
Total number of fields infested .......................
Average percentage of infestation for the comnmunity..


I l i l r ', *, ,
linlaed. m'he.
amined.


I0
20
35
26
,(r*6


1, 2
20. 2
35. 3
2V. 3
Joe, ,I


FIG. 7.-Cotton plant in an early stage of
infestation by the red -ipid.-r. Many leaves
aire discolored and some of the lower ones
have dropped. (Original.)


FIG. 8.-Cotton plant in well ad-
vanced stage of infestation by the
red -pidrr Nearly all leaves,
squares, and bolls have been shed.
(Original.)


This occurrence was one of tihe severest and most general that has
at any time come to the writer's attention. Perhaps the most severe
ease in this locality (and one of the worst yet seen) was one which
had its origin in a large clump of badly infested pokeweed stalks
:it the edge of town (fig. 9). The pest spread fanlike until it
reached in one direction a point cO- feet from the pokeweed. The
tiiail :ilc'eeled area. semicircular in -hape. coilnpri.sed 13 acre, and
within its confines the occurrence was gvienal. While such a ase as
this was a ii,-iial. 4-acre or 5-acre -Iot-. willth 2., to 100 per cent *l'iii-
age, are frequtiently to be seen.


.73..
. .. .. .. .. ... .. .. .. .. .. .. .. 7








N\A I HIA I '\ IWOI Iu N I \T -. iH .

II lN th the (isaIons if ]I;!ii l iln r I -Imi h r oc"murrn cv wis -
most severe ti.i',ii, ,',iii July aI ndl A:i i a .,i-.. Tll lai-l two weak-
of A\.1,.'.1-I HI both cases. however. wsit *- thie pest tiat by tim fi'l of tlaii monthly it waa haIirlla ii'it.Ii;l:hl. ias
a rille. This l henuImw m m, i hdtH'-d. 1I ,lpl n -uIl, hknl Ily, nIl tll-. :,_., ,,-
ci which wmork ti p)roduc( i n ;mr iunl -i.(ntl| i, I f l_ 1 .11 1ii ,o
value. I t .Il' I ., anld t1iL0"l,' 1 i O' of lln l] i ( a t al m t 111i1, ti He
iiatty {IicIC itIany ltuites t- [ l 'si-cr thi r(11lol tr o diicr plinl-. Ihut
ai1itolhel factor ojf liroldillly m .iiu _. ilvr imi|pum)o(;Hn i- th incr;'Qilu
allnl.lt.ll',, (f St^'erl' SlWH'viv idt ill('Ct t'l!'tlltlt' ^Iliflh SCC1H to, _' lill
,"toMiiitaivc at jnst thin tili..












-+.__ .:,:..,,


As -+ x ;i en d .i -
.*:.. ,. -% ....'.. .
... . --.,bJ -.





As 1,,. f,,*,. Iieintionied, cliimat ic counlit ion> exert a uiarkedl .uil, Ii,...
,p)on the w, .lfat're ',f the pel t. l)iiiii, times of little r.'irti.,l and
l~i,...h l,.iii~ierailiw,,ri,',,,1,,, liIIon goe.. on l)v leaps and bounds: on
the other liarI. li, iL. hea\ rains work havoc to the red-spider
p,>iihlilioii. In spite of the fact that the red spiders inhabit the
underside of the leaves, iii..111v are av.,'-li Ure de-t rovI'.\'I 1 ,V the iip\\ ;rd bombardmnent of sand particles, which
may ahvxi.. he een ,,,:tit*,.. the lower leaves after storms. In f.i, .
it :ilpca r- true that a I'." hiea\a rainsI. u-lii ii1ll if they continue
For somiie time, accomplish 1as inchi toaanl'ul controlliiii_ the l,'-l as


Till; i 1- -1i'll0 0 l k t '-11N.






14 THE RED SPIDER (IN ()TTON.

anylliiijg which can be done by man duiiring the season. From ob-tr-
vations made. both early in the season and at the beginning of win-
ter, it is doubtless true that the yoiiiig Htige, are killed by freezing
weather. This naturally prevents any considerable winter increuI-.
and in addition some adults probably perish.
The influence exerted upon the red spider by prev.isoni l condi-
tions appears to be even greater than that of the factors operating in
summer weather. The winter of 1911-12 was the severest in Soitli
Carolina for many years. Hence it miglit be -.Npected that the fol-
l,winlg season would be a mild one. from the standpoint of injury
by the red spider, through the assumed heavy mortality of the pest
duringn ii' the winter. On the contrary, as has been stated before, the
1912 occurrence was the severest on record. The only possible ex-
planation :1ppear1, to em-
V l brace two -iippoition,-.
SOne is that the adult re'I
spider is little su.-ceptible
S'., to extreme cold. Tin,
}....>.. other is that the in.,.it
S" enemies of the mites su,'-
-" "' i-I cumb much more ea-.il
... {_-"/," to minimum temperatur,-
Sr .... than do the mites themi-
) i selves. Both of these li-
0 potheses are slist;iined l)v
t all observations of tlie
Fi<;. 1O.-Arhrocnodi.ax s.. a predaceous enemy of writer. N lt lnira ly, then. ;a
the red spider. At lefi, mature predaceous larva, severe winter is preci-ely
S60 times; at right, adult female, greatly what would most favor
enlarged. ( Original.)
the subsequent increase of
the red spider through the destruction of its insect enemies. Con-
versely, an abnormally mild winter, free from decidedly low temperia-
tures, should furnish conditions most favorable for the survival -f
the repressive species, and the infestation for the followii,,. sea-,i'l
would be mild.
INSECT KNEMIFS.

Hot weather, although favoring red-spider development, proballv
encourages even more the increase of insect enemies, of which sev -
eral have been observed. Were it not for these inconspicuous friend-
of the farmer the depredations to his crops by the red spider would
unquestionably be more severe. "lie, followil,-n are a few of thll
n0ore important beneficial species observed drilling the season of 11112
at Batq-iigr. C.








1i t -i i li's i; 1(10 1m1W l "-ec. i f r 'J 1 "*.
of :1throcnodnx. i 11N|v I,.t, ._ li. t, the t1in iil\ Ilonish, I foH 4rme l\
t'v'fr l, iiht \')I, Iuta li:St lit it ed. (o nrd t lin l a i I il l. at \tih
lii lv I I a I o s- IM ; I Iall CoI on III 1 1t iic sM d I
t,\'r, aid hd tha i'ind of *Jlily h~ii l Ix'1u ,1iill ;l tiihtls Il. It i. inw
larva u_'ril, -1.i_,1, : *>i+ thil- ii-cr-t a l linlI i-il+ the f~iruiwr. aiiId the
Ilttack IeIl, to I lH li (iitfd eilt irciy t, tile l *l.- ihie -:- (I .,,,,,- in-
1Ct lltilt w itlh ani -. th1 lr int-t-it t 1 -I I til't-l \ i1. I I II, I i i. i_' rI
illir,,ni l, tilt' slI, ll aibii P,,.._, i.-' to> ftW >LI, ! L, ,., hl;rv+ w ill ,h.vour iil
.... ill fi' ii oh ei toI tIwo iililtf- aw lenlr tin -i-n lhr. lar I', I._-iIt'I
M rti'e tti e+. ae +ori' liii' to ht ir tie. \\Wl ,n hii ire. tli l;i:'a I-linI
a \\Ii S I I cov oo i I nI I.
lI If fi-,l lI I t I I I I I t w, I



i, .l,. t:1,.,. anit tile
L 1 -11 ct ll I it 11.
lltth ti l hI+ adultt



I'h. lve lwnltya of the Iot--.
ton miite. andl to its lii i3 1


lIl t's1iimnllr deciluitionl
qf the red .p.to. It
vi lc m ( t' O ,(,,,,


tas been re1ortle.m d frIi( it 1
the ,,ll,,v, i hlod elities:
.\ lla h ..i hi. AXiueromu ,
I Ute-Iui't,. Htroawn* illh',. LF 11 +i p: .... 1 ll,
:ll1 S t. \ Al I the -. S ( .; li al all A l l n.+i a ihi.--
( lihi-. ('it v. V a o. a tn.tr: ll**
(.i. i a id Alli ilh1 ani Blaz, Alhi. It evidl itlv lila a wile d i-tni
aut IIIO-Ir


Ii~ ii I ly e ..i i k i lt4 i I
I TI;I ,hl I ,N ;, o;/7.++,, I a l I. li t... Iil~ Ii li + I. -I
;i h/i/t ji ;,In /;u; ,,., >ia. ait a- 'lI'I rla .i M ia I>. It i- Ic Ilier"i]I
than the Arthrncnodnax andi aiji,,. tiri earlier in the ea-on. Thi,,,i_.li-
oI -t rill\ ;n i AI ,.'i-t i i- eIxtr i t'l 1o1iiil n i ;i tl ti in thI
tiyiiihial nlid Ih(t lt it.1 '- i se .onldi only- to tle ith nii a-' a rted
ptider eiiuitv. ('iil'- iil}>on ai red -I Ider. like a llH l> tle na iilt
thrlstt its -liirai |Ittoldu-'is thl ,i,''1" tilt' l>;'-t- Ihlk anid rlrceelid
quietly to -i]'1i, otill tlhe lho~d ct'lntent-. Tileh lhr+t v'letn o111siiteredi
was drained "' in nliut live nimilte-. lhit eat-i m cteeelti'< n ';l 'a :1-
of -h|orter dtiraithol ais thile +a|ppetite e!icialtle ---ati-If, 1 TIl e l itlolll
of the nvnph (1i_, 1+2) iare -.inhi'ir. hit thie indialitiial-, th!sera ved
were seeni nliv to desttov ."-'- of tlhe -litheti. Ini tliii ,]>er!atlt


1 1 ltl:111 l'I'lll]> 1I N I. \( O N .


I d.l< t irnnn, tt-%n t ltv Dtr, E, \'. F"'rl.






THE REL) SPIDER ON COTTON.


the proboscis was not inserted far into the onvumin. and two mIinutes
sufficed for draining an egg.
A species of lace-winged fly (Chr1-.iiq, ju'iin,, ,,1,f.dI linrin.,
determined by N. Banks) is abundant at BI ttc6burgf throughout most
of the summer, and its larva is doubtless vcry active in reducing the
pest.
Two species of thrips, Euthrips f,.,, ". Hinds and E ,',v .ta;
]vrrga ude, have been determined this season from cotton. They are
commonly found tIhiirolghoit the season about red-spider colonies,
and may be instrumental in
thiips sexmwlilatus Pergaide
has been recorded as an enemy
of the red spider by Periyaide
and by Duffy.
Lady-beetle larv ant ad Idllts
u of several lI)ecie.- are com-
', lnmonly seen on infestedl leaves.
--These are usually either (',-
U. (oiwlla 9-notata Hbst. or ip-
podanmia convergens Giin6r.,
*but a .mall black -pecie-..
ll L (S,.!/ftii,) Stethorw pinufiiun
Let.. is frequently observed.
Tihe larger beetles are prob-
ably more intent upon cotton
FiG.12.-Triphlcps insidiwosu: Nymph. ',v iy le but t las-n ie
enlarged. (Author's illustration.) aplIIdes: but the last- mentioned
.-peieN, although later in ap-
pearing and not overnumerous, seems to be more restricted to the
the cotton mite than are other species.

REMEDIAL MEASURES.
PREVENTION.
From the abundant experience of the past two year' the writer
has been forced to the conclusion that the eradication of the red
spider must be accomplished through preventive efforts rather than
rel)pressive, if it is to be economically effectedl. The location of the
mites through the winter and spring. their preference for the culiti-
vated violet and the pokeweed. and the manner of (disper-ion of the
pest lead to the presentation of the following cultural expedieint.
('lean culture.-First among preventive measures against the red
spider is doubtless that of extermninating the weeds and plants which
breed the pest. Pokeweed, Jerusalem-oak weed. Jamestown weed.
wild blackberry, and all border weeds and underbrush about tieldis
should be burned or grubbed out during the winter or early -pring.








'T'l]- plan Ihas l en tested itn -t ve al iitslants a1nd i Ias l.i,. ,.i i [l.('-
imniniility the fo||ill-- **'easo. T'JM ) uh "101 V .-i- can nutl Ibe
pl1h'cd lon the iipituidlin'c (i"f oivtroy i fair ;I- Iposilhe, nll wed,-l
Pr t,, I- e(sI I)t i.il1\ the i lk cwccl. wh i ..lii d IHt ilIb,. "li y
in' rooI t S.
('oumt," ,l A i n. A- I -' 'lt. l iefo si atold. tois, t clltes of i4 f "it lf tlioi ill
r'bail l,,,niili,', have thlicir ,il-'n ill hordcr+ of (*il ti viohtts
"r'r m iig, ill near-ln' i eor, srl l.s. lii ant' Inil ill-lii i t'- a ioltt iidjo, ii
iil,, Iit',- pa' 1it s tv sl lniiliil iinf t'itiol ii lim \ iW li t,,ii',, lily
.pr:ivil. with thte rv'-'it, that io redil S+i&trs appeared mI nlih'quiit ily
in these Ii~ld-. The ,,Ii,., ii. ,ii tt i1 i tretilic litl i lite faillmr -ii tit
p rli 'f the a\ 'i.,, p)tT'rson to ltere ert- t \it ih tlthe i)t ii'" iulitil tihe
p.'-l-. haive lbe'lln entirely xterillilntd. Thle ,liioit alitisfi t,\ pro-
cedure inll sulch caliei c(li-l-st illn lit I'ti moIval anld de'trutliioli of the
th ., I'd il,.L.1 violets.
lVarictaI imnIii+i,'f4/ t#f rotoi(il- Fro,-ln -, t'lsral ltests iondiitId in
di t\'erl(i tuik.l> with niumneroils i iandtlard vnrieties f tot, ntil fromll
the iiitmorin.'iI vodiunteeretd li farimeri froiiii iaivn portiolns of
Soilliti ('iirolina. data have Ie',ll icuulhttemId which cleirlv indicate
that certain varieties are susceptille to red-l'ir infestation, ,li1i,
itihlei- exhibit conl'idetrable imiluniitv. Carefiil obervat Iions on a
ci'ni-idelraillh number d' varieties ,i'," li ',i e tlOw purpose showed that
Dixie Vill Pri of.'" Toole. Iil'rnl kii. roandwell.. irid C ook -ulTier
numst ( in the order iiniieI) froni the attack of he pest, \vhile Ilite.
iu-'l, ."111 Si11111ii1'i'riil" "Half and 11alf." and Cleveland slihowed the
gretiil t iini niiiin il of all the varieties ii, i- ;it.led.
,,,,t ,.t.' i, rotfi.--AI n opportuinlityv was atccideit a llv proviled of
testillng tie' Vi"li of thlickly 'rv,.il'.-ii-i:.' cottwi at the olndilary of
a tili as a trap crop for red spideis. Thiis cotton, intended as a
cover (r1,0. intervened between tihe cotton field pro..r and a 1,l IILu.
heavily infested border of violets -a former abundant source of
liigT-aiion. Til, liroadl':-i,.d cotton Ibecame ini,-i. I and was later
plu w.il in. Thle adjiiliiig tiIi rlliiii,'I free from mites. The s.c-
cess of tlii- experiment would st ri' i .l\ indicate that the cotton trap
crop is a practical cultural e\pc.,Ii.il to lie used in controlliii_ this
pest.
,y/.,',/.--Ex'. xpriments at Ba l't, -ii',. ('.. have shown that the
red spider comnimiionly travels between plaints illtponl tle roinld. lii,-
-Ihows ine fil ilily of -p,., iil..- as a remedial measure.
TVn;,, ,, i1,1 f4r'i.-'ll'r. is yet muli doubt as to the relative .,-
antiitnL e- if early and late p ,ii iiL,.. Extreimely earlv [1,.ilii,. niat-
urally permits the plants to .dehel a llaxi illllii ,rtl of weed
and fruini l y the t inlet, of serious mite :iti i rn'e. It is itti'eable
that plants o(f i'li-i' itrai'lil, size are rarely killed by thie p'- -Il nor ale
wll-i-,dvanced I11ll. comilnlonly shed flroi il!festationl. ()On the other
hallni,]. several ti.IlI- about LAeesville. -. C.. whichh 1,were l 1i iied as


TIIE I lI -I'I1 I; I N 1 ( TTI I N.






THE RED SPIDER ON COTTON,.


late aIs Junie .21 seem to have largely escaped [lie infestation which
was so ,,tiT;i1 at that locality. Late I1d:inting. h ,owever, is almo..t
universally ,,bjectioinaleh- to the farmer. -nice in ordinary '-easlnls it
results in a reduction of the yield.
otation.-aIn an efiorlt to test the rotational value of other crops.
numerous field crops have been planted in or near iift.ted areas.
In addition, frequent examinations have been made of a great many
tardlen and 1 ,eget:alh crops in infested localities, e.ide- c ttor.
red spiders are known to occur not at all uncommonly upon thle fol-
lowing, field crops: C(\pea.. clover, corn, 1,p-. and watermelon.
They are also found frequently on the follwiing garden crops: Peao..
beans, onion, itoaito. lettuce, okra, turnip, mustard, -.qiuash. beet,
sweet potato, and strawberry. A really acute infestation on corn
(as above recorded) was seen at the height of the past sea.-on (1912).
Cowpeas are particularly attractive to the pest. and -weet potatoes
have been noted to be badly infested. Should an immune crop be
found and employed, it is extremely probable that the pest would
reinvade the fields upon the return to cotton culture with as great
ease and quickness as it has done d 11 ri:g a ly previous .eaon. provid-
ing the sources of infestation were yet at hand. lltat D in. then, does
not promise to contribute toward the solution of the problem.
Effects of fertilizers.-A rather elaborate series of tests with fer-
tilizers has been conducted in an attempt to determine whether the
various applications assisted cotton to withstand the injurious effects
of infestation. Since almost no infestation appeared in these test
plats it was impossible to deduce positive conclusions.
REPRESSION.
We have just discussed cultural measures which may help to pre-
vent infestation. We will now consider what mnay be done to combat
the pest when it has already gained entrance to a field.
The writer believes in prevention rather than cuv. in the case of
thle red spider. When once well established in a cotton field the
pest is a most difficult one to wipe out. That it is 1,-ilil. however.
to eradicate the pest from infested fields has been demonstrated be-
vond doubt, but in many cases the task is so tedious that onlY the
most determined farmers will iindrhr.,, the effort necessary to accom-
plish the extermination.
Rim orvl of infested plants.-The experiment has been tiho roughly
tested of Iulii,,r up aind1 dh-tr'vig the first few plants which show
infestation. In such cases the operation was repeated several times.
greatt care was observed in lor.it i n-ii\ ever,'y plant showing, the cliharac-
teristic red spots, and these were carefully taken from the field and
burned. If infestation has not advanced far. this treatment is
usually satisfactory, aind a red-spider invasion often may be nipped
in thle bud and entirely eradicated.







TIlE RED SI'IIIfiH ON 1toiN. 9

If infestaltion Ihas -1'01,iA 111ild 11 j on. ihde 1ut 1h 1h1* w e lome.
involve o ed it is soilet iills aidl i ale Ih. i.n l t w se (f :I largi e ti i i. l'.'
III all tie i trecvted iporti i i L ()i I etI oir -lo ka the i', itlluI ''i tf lt e i 1.1.
*',il,'li il dl.i-li,' liletilslre, howetver, ++idio ld ul v o li e resolt+- rledl to il tex-

trene k ;ie-. -Id tilt platter CoIicerntIld I IusIt Ie the jl. I I f its
adl isaiklity.
()ci. :-,1-i ,.,I otbservatiions ,i"| instancesr whereini illfn te ;t inn had
abruptly ,oippld, at a ui lich-trai veled roid -i.c-.'.,-i,' I thu i :' i of jilow-
iia ia wide v watli j it oI I t h' 1e I c Itl I Ia v of ilife I lat io ii. 1 I,, 1 ;i
atienIpted in Iw m Ia \% ere whti II, r lI 'lrc li'iad m red )init *J
Weres,. A li) f',oit rii, \Iilr' N a l wdti ii aroun\- tie p(it. aid i all -i i ,Il-.
hit lih in thle i ath nlili iii tIe inii I '1 ii, ,i :ii:zt Iv t l fariirlI r did Iii-I l Ii I hiI lit' I ;i l i ivo i t it1
ouiterniw t Zollet of inlfe tation, a tin,! i-li liti: I ii iu it it i III'lIilT w
of .ailt., I p11- lant's reInIain-1e1 o/Itsid t' l ,i. ,,iiv trizrl iul>irricr iio rol-
ili ii.. so ii ewhiat. thle disipers-ion of thI pit' -. I ii t'a lioi!l I In'
gi a ii % II' rlli r Itesit I i t e it therI Il d Il IIIe i, III ,1, 11 in lie
i>|n-r.'itii|,i. provided ttie sw\ath~ is kept stirred+ frc, lctlvlil.


II-'l4 fir tiii pUrpose wia about i ac'r'e ill xtenit, (it1 inlt t'- tinn li.l d
h coiiie hiutli very .''.i, i at tind ve v teveret. A sirip th:,.i.-h ti' lliiid-
1ih, i'? the flp tI. ,'i h_,- eacli s (priyed I plat, wi lef nn- 1 ied toill
.*'l'l'r as a click. Silence lino sllhbstaieliit' x1as discovi'ced wli:lx h i tl lIe
*-iifl, l ised to de1trov ill ."- in one kiplli:kioi[n. it Cx- w i ti l.l l ie -
.:I1\ to spray twvic.I, w itli ai interv la of -ix o1 v 1e 11 1; is. ro ;i- I t Id -
stroy the hilt'lii-'" lia va'. li, I, 1Hiiw- :il iity of l tl hice-v -I i ,I wis
ilon puted, alnd tilt ] i, iii i-eI I tII, i \li ie o lii 1 it I;cl ,f I II
lI' ,l||, ii six to liilc initionsA (-tin I TaollI IV) \ wi A foulild to i I v
.-it i-'.i, lI i \. ] In, aiv Ii'ar ep esltedI to iJ diic;te i the ni l n etr of pa lt GAi-
(l pil. i', thi. with tII e coI t. f o 0l l _i lionI l of eaili.
l'l'l |M1 I .--K
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Water to miaa.;e ii..l.' .. -. 4-






THE RED SPIDER ON COTTON.


In the course of spraying tests againstt the red spider on hops in
C;dif,,rni;i. conducted by Mr. W. B. Parker,' of this bureau, it seems
to have been demonstrated that loumr i,;i-t. used alone or combined
with caustic iiattrial.-. is a valuable acaricide. The function of the
flour paste appears to be twofold: Used alone it glues the tiny mites
to the leaves, and when added to linie-tilpliir. or other solutions. it
serves as a spreader to prevent the spray fihm from breaking up into
" beads as it dries on the leaf. Mr. Parker recommends the follow-
ing formulas:
I. Si,-.k solution of flour paste.
Mix cht';il wheat flour with cold water at the rate of 1 pound of flour
to 1 gallon of water. Boil to a paste.
II. Flour-paste spray.
Use 8 gallons of the above stock-solution paste to each 100 gallons of
water. Keep constantly ;igit;iotl while spraying.
III. Lime-sulphur and flour-paste mixture.
Use 4 gallons of flour-paste stock solution to each 100 trIllons of lime-
sulphur spray.
During the recent season no serious effort was made to test addi-
tional insecticides. Further use of the :ira vys .mentioned, however,
seems to establish the superiority of potassium :i'lpliid. lime-sutlphur
solution, and miscible-oil-tobacco solution. The last preparation
seems to possess better lasting qualities than the others. .ince. in the
absence of rain, one application will also suffice to kill a certain per-
centage of the hatching larvae. If one of these were to be used in
preference to all otliheri-, it would probably be potassium sulphid.
This insecticide commends itself from every standpoint---cheapness,
simplicity of preparation, ability to kill quickly, and safety of foliage.
Altogether it seems to be an ideal red-,pider spray. It was found
that 100 gallons, when applied as a mist spray, about .ufliced to treat
an acre of aver:ige--izeil cotton.
S,,,,.;,,,/ outfits.-The sort of outfit to be used for red-spider
spraying depends mainly upon the extent of the occurrence. Some
have sprayed their score or so of affected plants with a 77.-cent tin
atomizer. While this instrument is very economical of liquid and
throws a misty spray which penetrates and blows to all parts, it is
not economical of time. The bucket pump and knapsack pump come
into use in cases of considerable scattered infestation or for the
treatment of a few high plants. The most economic outfit for a
severe case involving several acres consists of a barrel pump carried
through the field on a w;agonl. One man drives, one pumps, and one
handles each sprayer (of which preferably there should be two).
Thorough treatment of 3 or 4 acres per day is readily obtainable with
this device. For safe work, however, this outfit should be used only
1 Flour paste as a control for red spiders and as a spreader for contact insecticides,
('ir. 166, Bur. Ent., U. S. Dept. Agr., January :'n. 1913: The red spider on hops in the
Sacramento Valley of (nlifornia. Bul. 117, Bur. Ent., U. S. Dept. Agr., 1913.






Till. NIED -PI 11l I: ON t IO tF N.


o i cootl / ( I a 'r 101% ii' r lot w ,i', .s i p i ".iL, w i_" ',i willo iiji ure
h, ri.' plans.
.e.\ t'c'fu !or el, ....... A ./ntii' ",.'/.- -Somel, di sati,.faction has !been
e ipelil".,I', .inI.,Ii-- cerl int f ( hos who hate undetak n to c ellck
the rI'\a :i' of the red spider bI -!,i i\ iII I I I I Ian lei understood
ii n IcountII of the xtr'i'ill car \,hich ili i't lh i' x i'ri'd in orwld'r to
ecucll e ,11. live results. In fi: 1 Ill, of inslects W,,hi 1h d \vour ihl, plant
tissue even th : careless aII1lip. at iK o f Pari 2.,ii i, r IAi h n a rsen;, t o
Ille top f'i the l'lii.', is often el iect i ve. This i- c \x laiuinud I[ the fI t
that such pests arc coustnitly i 1o4ii,. fnh )i li f li' heaf anid will
eventually tea It Ioit of tie oi s i-ontld t i 1ui'. Moreo' ,I ,. hI Ic- in 1i'ect
,ftini eat entirely vthii', lil tih leaf, iand he'nc it mialetr' little lhetht r
the poison falls upon one side or th, other. Wilh th i red -piilir,
cliievcr, it is :iltoi i flil:'I dilliii A contact insect i'ide is aidsolutelv
liic -.air, and. froin, te t t tht tlie mii e as a irui v pa-sse its entire
existence upon the underside of a -i-IL'l, leaf. it It'cmnomes plainly
Iiteee--;i,* iln spray ig. to hit1 tb, ,, /0 r; 11 ,f 1 /l,, f , 0 , /' f"i of an
iif.-tie.I plant. It is obvlious,- therefore, that indiffrent ci prayinig is
certain to Yield Uisi-l;itory rc-sults. liiurihernior. lie albolulte
n(lssity for a second [i:i\ i ii- to kill the hulatchld ,.- adds to the
difficult .
It is h,,l,.l that this discussion may imprve ipJin thu reader the
C(u JJIJ "I "U' h' itn of in festatio4.
>1STMARY.
Ti' t,' lii i:le red spider. a pac rii,-- o lie niaked eI h lik, a dot of
re'ddi-h ink from tihe point of a iii& pei. la bys- aoIt All or oi' i, inl.
olorless "Ir'--.! which hatch in I uiiinn1er linnl in aoiut fouir d;Iays.
Tli,, color'les, n, born spiderI liar si x I1';-. feeds atI once, anild molts
in two d: v, to the priniary iynmii.
Thi- ir-' nyniphial -.i,,r (and all later sl.i..'e-~) pos1,e` *1 I(, IV0h 1 -.
inI hi:i- h'olime lI.ir-"'r in size ;i1id, darker in color. In lwo niore in yv-
( in -umniimer) it. in turn, molt- to the econidarv nynlph.
The second nii\ l i.il -tfi.,v lasts t1wo dayv-, at the end pf which time.
litfler iiill, i ir (, the fully forImed adult 'ii'rl '.'-, M iiing o'ull s at
once and '.ri laying -ole inncdiately afierwaIds.
TIlS olie generation requires, iln lii; weiatier in Soutih (Caro-
lina, Abolm 10 (or 11 ,.]i\-. "'I l r,, are plro ably a ollt It" or 17 airt-
tions i n :a .*r.itl I year inI that I ocalit v.
'Th, red-spider colonies live on the lindleride f the cotton leaves,
il\,] ltiir constant feedlii,,. causes dlooti-red pot to i|>p,.ir on the
lop- of tlie leaves. The ," i uili, the cotton ililint is that the leaves
,rp. one by one. until il-mlvi1 the plant dies.
Thlie pest increases and spreads lllmost rapidly illn hliot. dry weather
liilt6 (towNard the end of Ail'_li-t ) several acres of a hOld may become
b:ily da:ii: lgel.




UNIVERSITY OF FLORIDA
1 ll 1nlll1i i1111i I N 1 1111
22 THE RED l-'riDER ON L'I 3 1262 09216 5785
S''irril insects have been discovered which destroy many mites
and are thus of greia I1.ncf.it to the planter.
At the end of the cotton-girowing season most of the red spiders
iir';l which are destined to survive the winter probably settle on either the
cultivated violet or on the l,,1keweidI.
RECOM MENDATIONS.
(1) Cl(an culturi..-l )-t r, by liurning and grubbing out, all
weeds and uind(erbrush a;lotI cotton field,. being i-lpecially careful to
remove all pokeweed. Practice fall p)lo ing so far as possible.
() Control on iolets.-Destroy or tholr, ighly spray cultivated
violet hibfnts which may be .Irl Mii ig near cotton field'.
(.') Rlbs/funt ineties.-In chsingl seed for tie crop avoid varie-
ties which suffer Imost from red-spider attack.
( I4) road(.sfd trap bhrdne.-ThI h, kly sow cotton along margins
of fields at points where infestation has appeared on former occasions
and Ilohw these in about June 1, so as to interceplt andl le-trov the in-
vading mites.
(J) ldl.:,,, first F.' e,, 4ted sta( 1's.- -M ,iat'.a i I ;i I a I ', eful watch of
fields from thlie t ime of the earliest appearance of c((t rtn above ground.
so that the first attacked plants m ay be di,'tected. remove, I. and burned,
thus preventing further -prad.
(6,) B r;'ircr stip.-1In case a ,ii,-.idi.rai]ii area tf cotton hais be-
co(me affecte(dI before discovery, remove and burn i lle \wor-t of it and
then plow a 10-foot strip completely around the extreme outside of
the infested area. Keep this strip stirred frequenItlv to make further
dispersion (difficult.
(7) S/,, ,,/';,,,.-Apply one of the insecticides re I,, iiimiiinded to tihe
infested portion of a lietldhi I'tf,'r. infestation I ,bevmne- to) general to
pro)hil)it its use. Choose the pump outfit which ule-t siits the par-
ticular case. Two applications should be made. IThle ,ecimnd. a week
afi cr the first, is to kill the individuals which were vri- at thle time of
the fii -t spraying.
Unlike many otlhir pests, ilhe red spider has no \i\f. and spreads
mainly by means of its inY lh.-r. Mi-rration does not exti-nd far from
its winter quarters. This makes vcrYv man's problem virtually his
own. In other words, if his infestation al :1,- cIm.e. froim a certain
spot upon his premises, p)ri-,r attention to tlhi- -lpot will yield him
satisfactory results in spite of the negligelice of hi- .ighilibor.-.
.\ approved
W %, ES WiTT.C, S 1 0 J,
Secretary ,,f. i/, 7, n1fir.
W\-iHMX.',.,,. D. C.. Juini,,ri 22. 191.L.




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