12 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1944 
when added to wheat in extremely small percentages, were found to 
protect it from insect attack. One or more of these dusts may be 
found useful for preventing insect infestation of stored grain and 
other seeds for planting, if not for food. 
Laboratory studies on the relation of temperature and moisture 
content of grain to the development and control of insect infestation 
therein showed that bran beetles do not lay eggs at 65° F. or below 
and that little insect activity occurs until the grain temperature ex- 
ceeds70° F. Bran and flour beetles bred in grain of almost any mois- 
ture content in which plenty of grain dust or broken kernel- was 
present, but weevils did not breed in grain of less than 9-percent 
moisture content and bred only to a limited degree in grain of less 
than 11-percent moisture. 
Serious injury to germination of wheat from normal dosages of 
grain fumigants occurred only when the moisture content was 14 
percent or more. Baking tests in cooperation with the Kansas Agri- 
cultural Experiment Station indicated that loss of viability of wheat 
caused by fumigants apparently did not affect the baking quality of 
flour made therefrom, but that retention of fumigants in nonaerated 
wheat appeared to affect baking quality adversely. 
Observations on stored soybeans indicated that insect infestation 
was of minor importance during the first year of storage. 
OCCURRENCE AND CONTROL OF THE EUROPEAN CORN BORER INCREASING IN 
IMPORTANCE 
The general level of corn borer abundance in 1943 was the highest 
on record, the loss of field corn from this insect amounting to over 
$28,000,000 and of sweet corn over $5,500,000, and the infested area 
was extended half way across Iowa and Missouri and clear across 
central Kentucky. Early sweet corn from central Illinois to the 
Atlantic coast north of the Ohio River was heavily infested, and 
most of it was a complete loss owing to borer damage. 
Commercial-scale trials resulted in gross returns of $4S0 to $600 
per acre from spraying and $54 to $196 per acre from dusting early- 
market sweet corn with ground derris, as compared with practically 
total losses where no treatment was applied. A preliminary test of 
insecticide application by airplane in 1943 gave promising results, and 
this method is receiving further trial in 1944. Two out of 247 new 
insecticidal compounds used in laboratory tests gave favorable results 
and are being given field tests. 
Thirty-two parasite releases, involving 39,418 parasites and 3 :■ pedes, 
were made in 10 States during 1943. In cooperation with several St ate 
experiment stations this work has been much expanded. A total of 
457,000 corn borer larvae were collected in the fall of 1943, from which 
it is expected (hat at least 450,000 parasites will be obtained for libera- 
tion in 1944. Parasitization of Larvae collected from the field in the 
fall of 194ii ranged from 16 percent in a few Connecticut fields to 69 
percent in a few New Jersey localities. 
ANNUAL LOSSES CAUSED BY SUGARCANE BORER 
Surveys have shown that the sugarcane borer causes an annual loss 
in cane sugar production amounting to over $6,000,000, This insect 
reduced the 1943 yield in Louisiana alone by more than 200,000,000 
pounds of sugar. 
