5f) .\.\M Ai. Ki.i'(tin s (ti- I >i;i'.\ii r.Mii.N r <u- a( ;ki( "i i/ruiii-:. iu37 
liclds, more pari i«-ul;irly lo tlic striiis from 2.' to lid feet in width, arouiid llie 
(-djjcs of tlH' liclds, wlicii' the liihcnwit iiij; weevils had coiiKrej^at ed. Under 
favorable weather eonditlons tlie majority of the infestations in tlie treated 
fields were reduced more than Uo percent and in some instances the weevil 
population was reduced percent or niore. From one to thiee api)lication8 
were niadi' to these lield hordeis. dependinjj upon the ma>;nitude of the move- 
ment of the weevils into the fields after such fields were dusted. The cost of 
this method of control to determine its true economic value has i;ot heen worked 
out as yet. Addili(»nal work on the border trap-crop method of control indicated 
that larue numl)eis of pea wee\ils can be concentrated in the early i)lanted 
strips, where they can be killed by i)lowinjj under deeply and cleanly, but that 
this method cannot be depended ui»on to control the weevil, since the sea.sonal 
period of emergence of the weevil from hibernation may vary from year to 
year, thus reducinjj the effectiveness of the Ixu-der trap crop. In tests conducted 
with several different tyi)es of tillage eipiipment it was .shown that the deep 
plowin.i? under of shattered peas on the .soil surface with a moldboard plow 
equipped with i)roper coveriiifj; attachments prevented a large number of the 
weevils contained in such peas from emerging to the .soil surface. Imported 
parasites {Tridspls thoniricn.s (Curtis)) of the pea weevil, comprising approx- 
imately 21.000 living parasite adults, were released in Idaho, but no definite 
results were obtained on this phase up to the close of the year. Hifdogical 
studies disclosed that in Idalut the pea wee\il was able to survive minimum 
temperatures of — 10° F. but was jiot able to survive a minimum of — :;o% thus 
indicating a climatic limitation of its distribution as an economic pe.st. It was 
determined that the percentage of mortality of the overwini ering weevils was 
directly proportional to the degree of protection afforded by snow or other 
covering during periods of low temperature. 
The pea aphid continued to cause heavy loss to the pea growers in many of 
the major pea-producing sections of the couivtry. particularly in Maryland. Wis- 
consin, western New York, and Ohio. From the data accumulated during the 
past two seasons the outlook for a successful control of this long-si anding pe.st 
with rotenone-bcnring materials is promising. I'art icularly good results were 
obtained with a derris or cul)e dust mixture containing a sjiecially prepared 
spreading agent, such a dust being preitari'd by atomizing a sodium oleyl alcohol 
sulphate into the derris or cube dust mixture while it was being revolved in a 
du.st mixer. Field tests with derris and cube sprays or dusts demonstrated thai 
the aphid mortality progressed over a period of time, ranging from a veek to 
10 days or longer, after the treatments were applied and that the infestation in 
the blossom clusters and in the growing tips of the pea vines was reduced to 
a greater extent than it was on the entire plants. This latter development ia 
important, since the damage to the blossom clusters and to the growing tips of 
the plants has a jjronounccMl effect on the yield of the peas. Analysis of canned 
])eas from plants that had been treated by dusting or spraying with derris at 
the dilutions found to be effective in the control of the pea aphid showed that 
no trace of derris constituents could be detected in any of the peas that had 
been removed from the treated plants. The time of ai)plication of the treatment 
also appears to be a very imi)ort;nit factor in the economic contn»l of the i)ea 
ai)hid. and this important i)hase of the pr(>!)lcm r(>mains to be d(>\eb p(Ml for all 
affected areas. 
Field experiuKMits in eastern Virginia, in an attempt lo d(»terinine the n>lalive 
effectiveness of various insect icid(>s for the control of the corn earworm on lima 
beans, disclosed that the best control was obtained with cryolit(» dusts or sprays. 
In the dust form the cryolite was api)lied either as an undiluted dust or at the 
rate of (iO parts of cryolite and 40 parts of talc or sulphur. In the spray form 
the cryolite was used at the rate of M ixunids to ~A) galhtns of water. In addition 
to reducing th<* inunber of wormy ]>ods as comi)ai*ed to those productMl on un- 
treated plots, applications of cryolite dusts and sprays increased the total num- 
ber of pods i»roduced. Phenot hia/ine gave good protection against corn earworm 
injui*y i»ut faile<l lo show a siguilicant incr(\'ise in the number of pods i)roduced 
as <'omi)are<l to the untn>ate(l i)lants. Negative results wi'r«' obtainiMl with 
various dust mixtures of derris. cube, iiyrethrum. nicotine. an<l sulphur. The 
Division of Insecticide Investigations of this Htireau made analyses of sanvples 
of sh(-lled and luisbelbMl lima beans from i)lots that had becMi tre.Mted with 
cryolite and found that the lluorine residia* remaining on tin* unslielled beans 
(P(m1s) was in many instances above Ww tolerano' establislKMl f<»r fluorine on 
fruit (0.01 grain i)er i»ound). Analysis <»f th(« shelhMl b»>ans. however, showtnl 
in most ins(:in<cs that tlu> (luantily of fluorine on such beans w.ms well below 
0.(H grain |tcr i»«Muid. Analyses were also made of canned beans from cryolite- 
