FOR IMMEDIATE RELEASE July 17, 196^ 



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. 



Armyworma have been feeding in the whorls of late corn in northern 

 Illinois this past week. Although the damage resembles that of fall armyworms 

 and corn earworms, these are the true armyworm. In some fields, they are feed- 

 ing extensively on foxtail and other grassy weeds, and this week they may move 

 to the corn plants. Armyworm parasites seem to be present but only in small 

 numbers . 



Before using insecticides for control, evaluate the potential damage. 

 Remember that a corn plant recuperates rapidly from leaf damage unless the heart 

 or growing point of the plant is damaged. We do not know whether armyworms will 

 feed on fresh silks. 



Do not apply toxaphene or dieldrin to ensilage corn. Also, be extremely 

 cautious when applying insecticides if dairy pastures or hay crops are adjacent or 

 close by. Amounts of these insecticides as low as 1 part per billion in milk can 

 be detected easily by chemical tests. This is almost too minute an amount to 

 imagine. 



For corn as grain only, apply 1 l/2 pounds of toxaphene per acre or 

 l/8 to a maximum of l/U pound of dieldrin or 1 l/2 pounds of Sevin. For ensilage 

 corn, apply 1 l/2 pounds of Sevin. If drift from corn to pasture or hay crops is 

 likely, use Sevin. 



There is no time limit between use of Sevin and harvest. There is no 

 limit between use of toxaphene and corn grain harvest. But do not apply dieldrin 

 within 60 days of grain harvest. 



Corn borers are now changing to the pupal stage throughout Illinois. 

 This means that some moths of another generation will be flying and depositing 

 eggs by the week of July 20. In some past years, we have had three generations 

 of borers in the southern half of Illinois. This year's early pupation might 

 mean a partial to complete third generation throughout Illinois. 



Fall armyworms are leaving corn plants and pupating in the soil. An- 

 other generation will appear in late corn during August. 



Corn earworms have been more abundant in field corn in the southern 

 half of Illinois this year than for many years. Early in the summer, when moths 

 cannot find fresh silks, they deposit eggs in the whorl of corn plants as they 

 did this year. The worms hatching from these eggs have now matured and are pupat- 

 ing. Earworm moths will emerge from these pupae during early August, and moth 

 flight will continue until frost. Tomatoes, green snapbeans and sweet corn will 

 be the primary targets, and late field corn also will be attacked to some extent. 

 How severe this problem will be we cannot accurately predict now, but the poten- 

 tial is serious. 



