

Cooperative Extension Service, University of 

 Illinois College of Agriculture in Cooperation with 

 the Illinois Natural History Survey and U.S.D.A. 



FOR IMMEDIATE RELEASE July 23, 1965 



INSECT SURVEY BULLETIN NO. Ik 



This is the fourteenth in a series of weekly bulletins on the general 

 insect situation in Illinois (fruit insects excepted), prepared by entomologists 

 of the University of Illinois College of Agriculture, Illinois Natural History 

 Survey and cooperating agencies. It is designed to forewarn people in Illinois 

 of impending changes in insect activity and to suggest abbreviated control meas- 

 ures. These reports indicate only general trends. Each individual should check 

 his own fields to determine local conditions. 



Pupation of first-generation corn borer varies from 33 to 75 percent in 

 the area from St. Louis north to Route 6. Some moths have already emerged, and 

 emergence will continue during the next three weeks, as will egg laying. 



In this area, first-generation populations are low; populations for in- 

 dividual counties range from to 3 borers per 100 stalks except in extreme west- 

 ern Illinois, where the average population per county ranges from 8 to a maximum 

 of 12 borers per 100 stalks. Last year the first-generation populations in these 

 same counties ranged from 1 to 28 borers per 100 stalks. We therefore do not an- 

 ticipate a problem with second-generation corn borer except in this westernmost 

 area. However, we have not checked the first-generation corn borer population in 

 Illinois north of Route 6. 



Control of second-generation corn borer will be profitable only in cer- 

 tain fields of sweet corn, some hybrid production fields and extremely late- 

 maturing fields of commercial field corn. 



For field corn, apply one pound of diazinon as granules when egg mass 

 counts average one per plant and first egg hatch is observed. Carbaryl (Sevin) 

 granules may also be used. 



Sweet corn canners can follow their usual guidelines. 



Corn leaf aphid populations have increased rapidly this past week. 

 These tiny green plant lice can be found in tassels and on leaves of plants in 

 most fields. We have no way of accurately assessing the importance of aphid pop- 

 ulations. We do know that severe infestations of aphids are associated with bar- 

 ren plants as well as shriveled ears. 



Malathion at one pound per acre will reduce infestations. 



White grubs have killed out spots in some soybean fields in central and 

 east-central Illinois. As plants are killed, the grubs will migrate down the row 

 a short distance in search of food. Many will continue to feed until early Octo- 

 ber and will then overwinter deep in the soil ; late next May they will come up to 

 the surface and feed on whatever plant roots are there. This feeding will con- 

 tinue until mid- June. 



Little can be done now to control these grubs, but plan to control 

 these pests next spring. 



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