40 A.\M AL in:i'()i; rs of i »i:i'Ai: i .mkn r ny a< ;ki< i i/rrui:. vxm 
strains. iKtwrvcr. shows no coircliU i(»n iK'twccu n'sislsincc to llic Jtiiiii worm and 
resistance to infestation l»y sprinK-l»r<»<Ki hessian Hies. 
Sev<'re cliineh l)n« inlestal ions failed to develop during; ilie year. althouj;h 
in some isloale<l areas harriers were re(iuired to prevent migration from small 
Kiains t<» corn. Work to determine the offvct on ehineh hu^ lK)pulations of 
elinnnatinjr certain varieties <tf s)nal! ^rrains was extended to en<lennc chinch 
huK areas in s<nit h-cent ral Illinois. The results <)htaine<l from the<e exiK'riments 
conlirm th'tse ohtained in other areas and in(li<ate ;hat no iMMielit in retiiicing 
infestation can he derive<l from eliminatiuf; fh»* more favorahle small grains 
durinj; ye.irs of hi^h chinch hu^ populations. 
An extensive armyworm outhreak occurred durinjj the year in a number 
of States, hein;; most .M-vere early in the spring in Mississippi. Arkai;.sas. and 
Oklahoma, hut extending late in the sprinj; to Illinois. Miss(»uri. Kansas, and 
the more norlhern States. Ohservat ions made on liie control of this siK'cie.s 
indicated that poisoned hran l)aits without the addiiiou <»f sawdust, gave the 
best cor.trol. Experiments indicated that cottonseed hulls and alfalfa were 
fairly go<i(l substitutes for hran hut re<iuired the addition «if molasses, which 
greatly increased their ellicieiicy. Pure wheai-bran baits were highly effec- 
tive without molasses. Observations made on airplane dtisting indicated that 
successful control could be obtained with c.ilcium arsenate used at the rate 
of 1") to W iM)unds per acre, but that the cost was miu h greater than with 
the u.se of baits, and the method can be recommended only wliere materials for 
baits cjJnnot be readily obtained and where airpiane dusting equii)nient is 
already available for use on other croi)s. 
Although the habits of the adult corn flea beetle, an important vector of 
Stewart's disease of corn, are now quite well determineil. the biology of its 
larva in nature is as yet unknown. Work d\iring the year shows that the 
Inrva can develop completely on growing bluey:rass, oats. rye. and wheat, in 
addition to corn. In cooju'ration with the Bureau (>f Plant Industry. 7S9 
specimens, comprising 15 species of insects from corn, were cultured during 
the year for the presence of Stewart's disease. No new vector was discovered. 
INSECTS ATTACKING FORAGE CROPS 
Progeny of alfalfa plants .selected for pea aphid resistance have been in- 
creased, so a field test of resistant selections of alfalfa was i)ossibie in Antelope 
Valley, Calif. Populations on resistant plants in lield-plot tests were less than 
2 percent of th(»se occurring on tlie susceptible licld plot checks and on plants 
from connnercial tields. Highly resistant plairs were obtained from three of 
seven varieties of alfalfa tested for resistance in California. 
Surveys discovered i)reviously unknown infestation's of the alfalfa weevil in 
South I>akota. western Nebraska. Colorado, Oreg<m. T'tah. and Wyoming. 
An investigatiitn has been made to determine wiiat hazards exist in the trans- 
portation of alfalfa weevils in baled hay. A iuethod and apparatus were de- 
veloped which made possible the rapid examination of large (piantities of 
baled hay. The time reipiired for examination of a t)ale was re»luced \o about 
o percent of that previously reipiired. Examination of bales of alfalfa hay by 
this method showed that by midwinter tlu> infestation of stacked, haled hay 
does not differ essentially from that of cocked, baled hay, although the initial 
infestation was higher in the former. Results of this investigation show (piite 
definitely that small numbers of weevils survive in. or on, baled hay throughout 
the winter — one living weevil b(>ing found in a bale as late as March 17. 
Intensive ecological studi<'s <(»n(hicted in the (iraii'l \'alley <»f western <'olo- 
rado during the year showed that, in c<»ntrast with i»ther districts of the <»lder 
weevil-infested territ(try. damage to the lirst crop developed bef<»ri> the i)lants 
were sufficiently mature to cut- thu.'^ rendering inellect ive the control of the 
weevil by cutting which has been developed for other areas. It was dis<o\ t're<l 
during the year that in the Oiand Valley virluiUy all female weevils matunnl 
in the same year that they became adult and that iliey laid many eggs before 
the winter b(';;an. This appears to be responsible for the a«lvantage of the 
weevil over llu' crop in the spring by permiiliiig nearly all fcmah's to resunu' 
<»vipositi<m with the coming of the first spring warniih instead of their coming 
gradually into full egg pntducl ion. as in I'lah. 
I'xiH'iiments with sulphur and copper compoiuids for tlu^ control of the iwitato 
leafhoppcr on peanuts, eondmted in cooperation with the Virginia Agricid- 
lural I'^xperiment Station, have indi<'at»'d that th(»se materials ar»' not only 
effective in reducing the leafhopp*'!^ populat ions but that they result in a stimu- 
lation to the plant which mat<'rially increases yii^lds even when no leafhopivrs 
