32 AWCAL REPORTS OF DEPARTMENT OF AGRIC1 LTM1K. 1 
Chinch Bu^s 
Chinch bugs going into hibernation in the fall of 1951 were too few 
in number to indicate any need for advance preparations for their 
control. Later observations confirmed that no control was necessary 
in any of I he ( Vnt ra] and Midwestern States in 1952. 
European Corn Borer Research 
Low level of European corn borer infestation in 1951 
Fall surveys by agricultural agencies in 33 States indicated the 
distribution and abundance of the corn borer in 1951. The insect 
was found in 51 counties not previously known to be infested and was 
reported for the first time from Montana. The area in the United 
States now known to be infested includes 1,456 counties in 37 Si 
Over the infested area as a whole, the European corn borer remained 
at a low level of infestation. It was less abundant in 1951 than in 
1950. Although the general average population in the North Central 
States in 1951 was lower than in 1950, the insect was more numerous 
in parts of eastern South Dakota and southwestern Iowa. The insect 
showed some increase in the Eastern States, especially in Delaware, 
Maryland, and New Jersey, and the surveyed parts of Pennsylvania 
and Virginia. It is estimated that 35,812,000 bushels of grain corn, 
valued at $57 million, were destroyed by the European corn borer in 
1951. 
Progress in testing of borer-resistant corn strains 
Thousands of strains of field corn, sweet corn, and popcorn were 
tested during the year for resistance to the European corn borer. The 
work was performed in cooperation with the Bureau of Plant Indus- 
try, Soils, and Agricultural Engineering and various State agricul- 
tural experiment stations. A number of inbred lines have now been 
identified as resistant or tolerant to the borer. Among the important 
newer lines of dent corn having a good level of resistance are Oh43, 
()lii:». Olill. Oh5, Ohlc. W22, W112, XI, N32, 4295, A277, and B7. 
Hybrids K62, W64, W44, C54, C47, and L41, released by the Ohio 
Agricultural Experiment Station and designated as resistant to the 
European corn borer, contain the resistant or medium-resistant in- 
breds Oh43, Oh45, Oh41, Oh51A, and Hy. 
European corn borer kill obtained in laboratory with new insecti- 
cides 
In cooperative investigations with the Iowa Agricultural Experi- 
ment Station. L58 new insecticide compounds were tested against 
newly hatched corn borer larvae in the laboratory. Of these, endrin 
(Compound 269) and isodrin (Compound 711) were die most toxic 
to the insect. Twenty compounds found promising in this and pre- 
vious laboratory screening were tested in -mall plots in the field. 
I ' in lei- the low number of borers prevailing in these tests in L951, four 
of these compounds, endrin, isodrin, EPN, and heptachlor, gave out- 
standing kill. Sever other insect icides were as effect ive as DDT, the 
most widely u^rd insecticide recommended for corn borer control at 
the present time. In addition, EPN, one of the promising materials 
in the -mall plot tests, was equal to DDT in the field scale tests, 
