The pea aphis

MISSING IMAGE

Material Information

Title:
The pea aphis (Macrosiphum pisi Kalt.)
Series Title:
Circular / United States Dept. of Agriculture, Bureau of Entomology ;
Physical Description:
10 p. : ill. ; 23 cm.
Language:
English
Creator:
Chittenden, F. H ( Frank Hurlbut ), 1858-1929
Publisher:
United States Dept. of Agriculture, Bureau of Entomology
Place of Publication:
Washington, D.C
Publication Date:
Edition:
Second ed.

Subjects

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

Notes

Statement of Responsibility:
By F.H. Chittenden.
General Note:
"Issued February 25, 1909."
General Note:
First edition has title: The destructive green pea louse.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029676747
oclc - 83709477
lccn - agr09003053
Classification:
lcc - SB823 .A33 no.43 1909
System ID:
AA00020890:00001

Full Text






Al MO. 4,, WCOND REiTION.l


United States Department of Agriculture
i BUREAU OF ENTOMOLOGY, Y 0
l~?^i L.. 0. HOWARD. itntomloglut and Chlal of Bureau.


t miTHE PEA APHI library
p (Macronspma pa iKalt. \
.-. :.By F. H.CILITTEYDEN, -
ii;:hi: ... " ofeg Truck (Crop and Special Insert Inresligati
g 'H llP Bmost destructive and troublesome insects of recent years
'' plant-louse which, fromni its injury to peas, is known as the
H-. i ": u *" "
:: ....<


00 H... .P

I1. ]oL,.Ltl ph (JZrwm6pkiaiMag ): a. Wanted female; b. same from side. with wings folded In
SW:: VnOW a when reedhu;: e. apterous female: d. nymph in last stare. 0. third Joint of
"' U:".a. i twIseedform. a-d, Mucbenlarged; r. more blirtilymanrid'd. tAuthor's [Ilustraion.)

pe: a sh. Since it first attracted attention by its ravages in May of
I.S. it b9steadily increased in injuriousness, and has been the cause
| : f: tlar with sligbt revision, of Circular No. 43, Second Series, entitled "The
Ks l tru tive Green Pea Louse (ZVectarophorn destructor Johns)."
i^ (i.. Vswsl tniciss have been published on this insect, notably by Messrs. John-
": IN B Si amuon1ii U well as by the writer. The former gave it the scientific
,t." m flwhua *dstrilcer, but the latter gives reasons to show that this
'r BuM blen watt y ls Z~X y .la& a fI lt.; hence the present change of title.
;i .;;:::. :;:::; ". : ":: i. -- --- 9,
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25. Im.









of great loss in the principal pea-growing regions of this country, espec-
ially where peas are grown for canning. It was, in fact, one of the
most important of all insects that ravaged crops in the United States
during the seasons of 1899 and 1900, and there appears to be little
prospect, unless the unforeseen happens, of any decrease in its devasta-
tions. On the contrary, it is to be expected that it will widen its range,
as it has apparently already done to some extent.

DESCRIPTIVE.

The pea aphis is one of unusual size among those found infesting
gardens, aQd the largest of the green species which attack the pea and
related plants. The length of the body of winged, viviparous females
is about inch (4.5 mn.), and the total wing expanse about A- inch
(9 to 11 mm.). The general color of both the winged and apterous or
wingless forms is uniform pea-green, the same color as the insect's
favorite food plant. The eyes are prominent and reddish brown in
color. The antenna are lighter than the body and the tubercles promi-
nent; the joints are darker than the rest of the segments, the seventh
joint filiform and fuscous. The legs are long and conspicuous; tarsi,
distal ends of tibia-, and femora fuscous. The nectaries are fuscous at
the tips, otherwise of the same color as the body.
A typical female of this insect is shown in figure 1 with wings
expanded, showing venation at 't, and a lateral view of the same with
wings folded in their natural position when the insect is at rest or feed-
ing is presented at b. At c an apterous or wingless form of the insect
is shown, and d illustrates the nymph in its last stage. The structure
of the third antenna joint of the winged form may be seen at e, highly
magnified.
DISTRIBUTION.

There are good reasons for believing that this aphis was introduced
from abroad, probably from Europe, one being that injury of the
severity noted by a species of insect hitherto unrecognized as distinct
from others of its kind is almost without a parallel in the history of
economic entomology. It seems probable, therefore, that we have in
the pea aphis a case analogous tu that of the European gipsy moth,
which was present in this country for about twenty-five years before it
became a pest.
The first, notice of severe attack to pea that can with positiveness be
attributed to the pea aphis was reported to this office, in a letter dated
May 16, 1899, by Mr. Thomas Bridges, Bridges, Va. This was followed
within the next few days by reports from Virginia and Maryland, and
soon afterward injury was recognized in other States and in Canada.
During the previous season (1898), however, this pest was present in
A6--9


aIL








some nlumLlber4 in r'r'tin lin'lLs is n .IIN ryl.iini :i ; l w:t. SIitiaI't 1111 late
peas in New Jtersey.
This ins'rt, as hais li.'nii s.ita'l, %,i' t i.itr.illy injuuriu.ii- during til'
years ISl.) and 1901)), altlioughtl olnli'iiLt ar.ill i.'-ilili' Si:at, -, froim
Nova Stoti.i south t-i Ni- i th ';iilir., : ,ii1 r14 ,':. r it, \\'i.-,' .i1SIII. Tin
insect'\s IIcIrri'Licr i i ai"itrtilc1iie .iliinl, ll .IIa ;i,% iliata l In4 1.I.IJ) inll
Nova Scotia, Nr ltrunM irk.:itk, :iiI I)il.ria, (' .iin.iil. ; Ma.iiia, \Yrr ,r)it,
Masa'hluaett.s, (C',1inn -lit'ul. New t rk, Ntw .Ir.-'y. P' iiti-\ lv:iniai, Iutl-
saware, Marylaniii. Ii tlrict if l'aliinili:a. Virgini., NVrtha I '.irlin.i, Mi'l,-
igan, O him1 Illini Si., :il W icL- ii.i S iniih'r.-iii li:i ]ri'' lr'l lih
species as oct irrilig ILIl) illn Milii'-'l .I :iinI Na r'ii-k.i. Injury in W is-
consin was not nliti' ]ir prior to l!i9lli.
At intervals siicte lll01 tlii- spleris has in',ii ijiriii lsiu lua'lly but
there have heen no widlesprt' i mil br ,iaks. Iurinii h. l;a.:-t tlirce years
the species has tIetin rLthtr tini .inl:Illy 1 ro31 'iiil ini, judging 1y coin-
plaints. Inl 1906 iinjurit.es were ri''iiirt'il in l,'a:iliti(.. ill New Ytirk, \'ir-
ginia, Illinois, anil "Texas. Ili l'.1l7 the range ( ilf.-lr ti tia..S eniii-
braced portion of eastern, centrallr-, "n, i it.stUrn New Yirk ail pa.irls of
Maryland, Virginia, and thlie Dliriit (if CGIumluiai. Tri inil.S-t IsIo
made its initial aplpeiaraince ais :i i'.-t il I .otli.inl:t. In PHlilS ci iiplainlts
were inade of ravages on Lnii l.iani ;Inil, iLL Mar\lanl, Virginiai, 't.enn-
sylvania, New Jcre'y, :ii' l (':tliitnrnim.i. In N\w Iaiiiil.a-hira early iit.as
were dtstroyet'l a11n1 in thit,.'%lttr Virginia I.,t' pcis vera' inijurel. It is
evident from recent reports, e. g.. tilh- af iljinris. in Trxas, Laui.i:Lna,
and California, that tht lie Splis i likily i,, lat :l.-t :iA iy y. .ir practically
throughout tie t'litIed States an.i ('il.i,.t C\1tirr,11 pli. art- grown.

EXTENT or' IN.i1'HIY A NI I .-'7 l' IO' il % W' l IK.

This pea aphis duriiing tlihe fir:t sr.isuii of it.% iliinil.li.incet overran and
laid waste fields of pe;t- fromui No,.a ,Sr'ti:l ;:ii Maine' to Virginia and
Maryland, in tlhe l.ist ;iili inll staiint iiiilghliring Slitates lestroying about
50 per cent of the annua.il output ainl i',iig -iniliar injury thle following
year, in spile of vigorous tfTforts tliat it -r nfliLah Il t'Oniltrol it.
An estimate of thie taial loss fir- tElie year I'l!i in thle Atlantic Coast
States reached thet tuii af $ ,:;,II ili). IDurin, 19411) the loss over
the same area wts pl:iceii, as early as June l at .il $4. (H )I, X.K I. Several
cases of severe damage were reportedly in M.:rylandi, in whit h SO per cent
or more of the peas on farms of 51) Olr 610) aicres were completely
destroyed. In short, the pea growers of the Atlantic region and west-
ward as far as Wisconsin suTffered very severe hsses, which gave rise to
the expression that this country hadl been visited by a veritable scourge.

'There is evidence that thli. species w:is ,ha'rva'dl ,'i crini.snn clover in Dia-
ware as early las \ll, and lhas perliapa theiui pr*,eiit along the Pnitoiac River
since, or prior to, ISM6 (Bul. No. 26, n. s., [liv. Ent., I'. S. De-pt. Agric., pp. .-A, 721.
A -,--I']









The reasons why the species has become so conspicuous a pest are
threefold: First. because of its ravages to a crop hitherto little troubled
by insect attack, if we except the pea weevil, which has always been
present in gardens and fields for upwards of a century and has come to
be looked upon as a necessary evil; second, because it is a species never
before noticed, so far as records go, as having been destructive to peas
in this country; third, because of the great difficulty that has been
experienced in its treatment, pea growers during the first year of its
ravages having met with almost complete failure in the remedial meas-
ures applied.
Although garden and field peas are the crops most injured by this
aphis, sweet peas, red and crimson clover, as well as vetches and tares'
are affected, and in some cases have been damaged. Attack begins on
the young pea vines; the "lice" gather in clusters at first under and
within the terminals, and as thlie leaves become covered they attack also
the stems, and by their numbers and voracity sap the life of the plant.
Whole areas of vines are frequently seen covered with the aphides,
which in a very few weeks are able to destroy a crop. Attack is seldom
noticed until May 2 in the more southern States in which the insect is
found, and a little later in its more northern range.
The complete life history of this species is not known, but like other
aphides it produces many generations each year.
According to present knowledge, the pea aphis hibernates chiefly on
clover, particularly crimson clover, from Delaware southward. In the
District of Columbia it winters also on vetch. From these plants the
"lice" spread by flight in April and May to peas, which they attack
while the vines are young.
As with other aphides, the females at certain periods produce living
young. They attain maturity in from ten to fifteen days, and possibly
in less time in the hottest weather. Yuung that were horn March 4
reached maturity (winged form) March 16, or twelve days from the
time of birch, and reproduced young three days later.
As an instance of the rapid reproductive powers of this insect,
Professor Johnson's estimate is interesting. Hle found that females
produce from 110 to 120 young and that in one case where aphides
were observed on the first of May the fields were abandoned on account
of ravages three weeks later. Calculating from the average number of
'A considerable number of alternate food plants has been observed for
Mucro.%iphfml pif.%i in Europe.
2In 1901 Mr. Samuel R. Haynes, Portsmouth, Va., reported the presence of
this species in that locality about April 7. During the second week of May the
writer found it numerous on crimson clover and %etches at Washington, D. C.,
and May 14 it. was reported at work upon peas in the District of Columbia, near
the Maryland State line.
A6--49









inse'tA prodtLcr', I ..,lii l '1y. lii,"h is 0ix, on inldividu.,l would I,.-colin.
the puogtliitltr ,f '_'2l.!12 -4 ti, *.8 .ililii'l k ill one season.
NA.\ II I. I l. 1:I :NIIF".
Thet etlivivivy 1l ii:ttttr.id aL'IIt- in the destruction f l d l is so
well kitwnII tlai:it it lia-4 lvii lir..1 thatt some one or more of thi. many
species ol..rv'i il at I ii.L k tli p,'i api' :l %ii would increase in such numn-
btrs aS t1 l.l\,. til, It ff lt. tn
of Iiriiiiiii t ita- l il il i-t a
cation. III .Nui,. Al a Aav.'r,
e, i th, ,th, t..'t ,I,.t',,.itns al
by IL1tllI,'vr id I ..a'1 ll4, i
tih l le L a dtt l' 'linia t' h*.lt' l I
been fIlIld tij Proalu'e
only trandsiuit ri i-.lf, and l
thlis Only in li llii ,l as aT rule late in th' ^y':.ln ,
after damoige p:i, Iaist'- \l< G b ca
Complishetl. I a. 2 Sj.tlh I ladybird iMiwly al t*ahedf) a, Lrva
The present I ist of Ili- t, -m 'ty r ali sI it IITI, i. i v Ie Iartd Ia [nnal
sectskno,11 ,,,k e. Avi l e1nlarged, (Aut~hor'+ iilua tration.)
sects kn omi. n t ii att .4 k this "I'-%` on in d o
aphis inclualey sevr spec(i,' f lf,1'ir ll,, or S.aly ai Li t as they are






in 11ire of asd rp m rr.-rix2 a i. ly.
familiarly t lrnied.' I bra .ici Of rpliI tha h ,a a n., bee-ng tlye a
soldier beetle,' andi a fe' t.i i tiete fi pr-wi,,, Ii'vi ,,iiitiiit'raius parasites.l
The ladyhirl a, tl,.-truti, both as beetles and larv ; thesyrplhus
flies on1iy in l lral ttiiah ,aI, awv:1%hich is true aisoaf tlij. ., .-wi. g lly.
Thile ellicit'iy ,f thie f .'ri hins l'les. is r.. i.tly impalired by the Lpru'/e/ice
of a briaconiti :r:i:- itrl 1 lii ik somifetimles vvry iara.a1,.Lt, almost com-
pletely exSt; rn.'ln:tiling its liaa,:t in ii.ltY l iait-. NIe.rlyr all the specie!
observed are %o ]l-k!o n e,.ntijes i,, other .' ti l.-. and in fa,'t greatly
prefer as host. the clali)atga arel i llI, i,-s founm d on n P v.,ls to the
pea aphis. The srottta I,!,al ,iral (.the ,>Itl/ woluhIftt I )v, ;.) and a lace-
wing fly (Chry,,sij, i ablaf, Say) are shown in their ,litlerent stages
in figures 2 and : r,.ila.t ti .ly.%
In addition to t010 natural t IWeMies that have already been enumer-
ated, several other imn.-'ats. attack the pa.. .l ,|i.. alim ani g then a siII;Lll
red muite, Rihiv'''/,,oiJ. IA.-.rJilIs bahk:-.
Cocto(', nt ilr i e,,,.,.,,d't,, i, 11 t, t., II~ ~,d ,, + a int ','rnI, iji 4 I'li:l'. 1 1 i ll
flaaced ha hi e ; 4I ll I~ l.,4 i ,,,,11 q/,. o ,, ''-, .u it., A d a I,ai th II' 'i h L .. II 'jq ".,,Ia -
mactrla" e' ,ll- tI Ii ., It '?. *'1 /.I., ll, /a il laai,' ra. ,a .- o t hr J lr ,,l,d, ."al.,
'"!Irp h js. i, rrit-r in' i..; WVie.,l., at~ 'Ii,-ri,,r, vl;I t, ..t% 'Vhrtljrfl,, oel-
leelz Sa' '- I' ab rirg riiq,.'ilalh Lec. I.1 pI ah4,, i, i.l. ,. ,+,i .\ lii.
.M A. ?i.l, i t A. I t',hi, S.? ', Pr',a fr, ij a I-itch., Jsofrtrtfu oIE-
qarl, W alk. O ]i.-i.t, b ttalwr' FaIlP.
In the above li-;t the spvcivs t,[ each class are named in appr,+xh.iale Arler of
nbandance in Maryilaiad, Virginia, and the Izatrict of c'.,Itiabi.a, and caalsa'a1u,.tl
efficiency as destroyers of the aphis in that region.
A .----,9









Considering the inefficiency of natural agencies, if we except atmos-
pheric conditions, in the control of this pest, it is hoped that a com-
mon fungous disease of aphides, known as Enmpusa aphidis, may become
an important factor. As the development of this fungus is dependent
upon rather warm, humid weather and is retarded by drought, it is
fairly certain that atmospheric conditions, after all, are most important
in the limitation of this insect. It is within the bounds of possibility
that the fungus might be cultivated artificially and be used during
weather conditions favorable in the control of this pest.


b V .,
FIG 3 -A lace-wing fly tCAhnjsui, rci,,', E -ci. b. full-grown larva; c. foot of same: d, same
deviiurirwi pear tre- p-1ylla. ,. r,, 0..- ,i. f. adult in-e-t'l: 9. hoad of same; i, adult. All enlarged
except hI. which i4 natural size 1 romn Mariat i
METHODS OF CONTROL.
In some instances natural enemies of the pea aphis have rendered effi-
cient service. Seldom, however, do they destroy the insects early enough
in the season to save a crop. In the course of time-many years in all
likelihood-these enemies may become more effective; hence, in view
of the fact that the extermination of the species even in a limited area
is a practical impossibility, anything that can be done to destroy the
aphis without harming its insect enemies is advisable. If this can be
accomplished it will afford in itself a reason for the rejection of insecti-
cides, none of which is in all respects satisfactory.'
'For the benefit, of some persons who are not wholly famiiliar with the feeding
habits of this species it should be stated that it obtains nourishment by suction,
and can not therefore be reached by means of internal or stomach poisons such
as Paris green and other arsenicals.










KI ri.tinir fi Il.%inI.-l K rii, tiiii-.,iilIp pi'l iitlI,40 % .:liiii.ir'I r ,ulrily for
aphidles, var-fully preparcil re, l ililut 1lil 6 ;itii.I Mt twrlv, p.art-4 (l' f%.it i"r,
spruayel uljpon tlit ilifvtr-,Il llailt.S tLi1l tl fir lir-1 ;lilp''ir:llui-r of thlt
aphidi ,s, lind s') ;i]p, liu'l tlhat till' a.,\' rt.-, ir' \Mt til bolt l t iln l,.r aind
Upper surf.llt.es, li:i; thu.s f.," tb n fi I 'll l Il ti s' ,li ,lit IT.i i of tli.
insecticidlhs triv l. A .strmiiigr -i iutiuinm t ian I tlit .-|irili.,l i- :ipt It) l'urn
or s'ahlL tin- pl.tilt. Ipart iila.irly M ,hitl tli vines :ar, ,iiiig,, :iid Li i ,h.r.
ipriys uf htlial--oil .izil o lit er Sips l hi:ir, lit" ,i l'iiiiil \, '. .-'fiil. Tl'il
cost of thle ktrtir ,r ti'n il..-i i triIL, 'ly. l,,dVi,.r, :il till- llliviiIlly if
Uiiclersprayiig. its I ';a i'l v:I;IpIrt, P.ir. ;uti ii, rii,', .'.-ilt% I.ir I'n ii,' lit
:Lpj)]ic tiOhii:, lrt.' a it h ias Im rlly I ,to % mi.r it it- ui-, ', ti i lIr So .1i1'.


Flmt. 4.-S- 'rayvlni' l -iir | i% h -ti'thl halt 'il -,tn'. s il i111 lit i l r Tr. I:iIriilniitIh an1,]
ajijilii .ii**rr

The method of preparing tobahiri,-vI Ial-oil s0:p,. ;i ) spcial iiri'lF r at ion
of soap of particular value for apli Irs,. anil tlhe iiilrpmitents u.c-l in iiti
application are illustr.iteil b'y figin'e -4.
The bri.sh-,id-rn'llirnlr nmlthl.-The chest remedli.il mne.tssiri' thhat
has yet been tidviteI is tilit growing of peas in r,,w. witli ..itriient l is-
tance between them to ailmit a one-hirse cultivator. Tile "li,.'" are'
brushed from their plants with bnughs of pine with thieirleave.s 'n. :i nil a
cultivator then follows down the rows as soon aftcrwari as pi,.ihli'. For
the perfect success of this methnii it shoulil lie practi.ced in tit,' he.t of
the day, when the ground is dry and hlt, and tle- repetitiln -of the
brushing is necessary every three tu, seven days until tile crop is ready
At----4'J










for picking. Such lice as are not buried in the ground by the cultivator
will be killed by the dust which closes their breathing pores, while a
considerable proportion is destroyed also by the force of the brushing.
This method has the advantage of not being so destructive to the natural
enemies as other means that might be employed, the aphis being more
fragile and delicate than any of its insect enemies. Moreover, peas
planted in rows to permit of frequent cultivation suffer much less injury
than when sown broadcast. As soon as the last picking has been made
infested plants should be promptly destroyed by plowing under.1

-- '- ~ -' -- *"I*! sSiM?


0.... i l
..Am

." 2' 1 ..."



















Fin,. 5 -Field nf peas saved l'v brush and-cultivator method, showing implements used.

TJir brusli-and-pvin nieliod.-A method which consists in jarring the
aphides from the vines into specially prepared, long, shallow pans in
which a little kerosene is floating, dragged between the rows, has given
good results, the insects as they come into contact with the kerosene
being all killed. A bushel of "lice" was caught to each row, 125 rods
long, in one instance where this remedy was used. It is practicable
only for small areas.

'We have abundant testimony to the value of this method, but perhaps none
more striking than that on the farm of Mr. C. H. Pearson, a Maryland pea-
grower. During the season of 1i9i'X, a 600-acre pea plantation was practically
saved by this method. After other means had failed, the fields were brushed
and cultivated every third day for a period of two weeks. The previous season
peas over the same area weresow n broadcast; so thatit was impossibleto combat
the pest in this manner, and as a consequence 480 acres were entirely ruined.
(Bul. 20, n. s., p. 94; Bul. 26, p. 57, Div. Ent., U. S. Dept. Agr.)
A6--49









A field of ptais Msavvil i,.y tit,' tis, (if thl liri,-li-.iitil-t'iltiv.itir riltuil
is illustratedl in figure 5.
In figure 6 the naati.t'r of applyingl tliIr-l' l-:L.nl-,i in ,irtla,, i.
shown. Figures -1-7, illuIStratiitL tl, Irm pi ti(.l i-iitlii'l ,if rimmlii:tinIg
the pelL aphis, were Iirst 1.,ril iy liii l.ilq N% .f.ilil.-tiiii in :ii ,irti( It
published in Bulletin N-,. '61 o th tlis iluri.lni
Cultural n,'thul.-E )f cultural It.ii ,li., titr, is tr-tliiiiiy t., tl.
value of nearly planting, the ear~rli,-t I'-.i l lii Ii1;. iIIf,. .l,-l. ,r ;it
least only slightly injureml. V'.ry large, pil:,tin..-s if i,:.- t, I- )I. iii, l
for canning have almo esc;ape'l r.\.ig'l ill .Si1iitn il.-l.111, fV.'. I',tt it I,.,l" I-,


l'l. 6 --Feil of i ft'f s 0 il I',y th, Iru-h-i ,i'l-pan rnwth,,l. .hi t r it '. ,:ira tlu- ii-. ,I

that atmospheric -niulitinns lit.iv li':1I snnthiii tg l 1i1 UI itlt, i \Xiniil i,
in the cases which have onime unlcr ndteir.
Rotation orf crps is ailvi,.;tli'l, anal it i, tlun ise t, pl.mt pI '.t.- i' I ti!e
same portion of i fa.rii or gari len, i sn % uu' !.. i* v t.ir.s. air inl tll xi itit"
of fields of red or crinion t'li vnr, air aitlier lgh i-inioUS plantl-, -< u i a'
vetch, which are likely to li.irlor this .Sp't'it'M.
As has been sail, this insect paiss,.s tlie wintrr on ti]' pl.iits aiun.l-
tinned, bt t'ause p,.as are not ava il-tlhe, anal it n igiht lib Ip ..il. -,,
use small plants of sotn1" one (if tleim as trap crops. ('ristiin cl'\itr
would probably be best because tf its ,iilspii,'uoiusn-s and the e.trly
start that it gets in the spring. (On ti' trap plants the aphilts c'iuili
be killed by hand methods, such as brus-hing from the pl.Mnts int pan:.-,
A6--19


A









and thus large numbers of the insects could be killed early in the sea-
son before they had opportunity to spread to peas.
In Delaware it has been shown that the practice of keeping the land
well fertilized and frequently cultivated enables the peas, in spite of
aphis attack, to produce better crops than would otherwise be made.
Alternalp host plants.-The subject of alternate host plants is an
important one, since the pea, being an annual, is not available as food
for this aphis during winter. It is desirable to ascertain all of the host
plants of the pea aphis, and more especially the weeds, as some one or

.*,. .,.: '. .


:", '.:., *. ".' '


.5L"


FIo. 7 -Section of a 600-acre pea field, rows one mile long, showing spraying outfit ready for
work. Peas finally saved by bru.h-and-cultirator method.

more of these may be factors of importance in the life economy of the
species. It might be necessary in the future, should the depredations
of this insect increase, to limit the growing of clover and other legumes,
as well as other alternate host plants, if such be found, in the vicinity
of pea fields. if all of the principal alternate plants could be discov-
ered this might furnish a solution of the problem of how to deal with
the insect.


Approved :
JAMES WILSON,
Secretary of Agricuilture.
WASHINGTON, D. C., Janutary 21, 1909.


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