Cooperative Extension Service, University (rfSc ygftARY OF THE 

 Illinois College of Agriculture in Cooperation With 

 the Illinois Natural History Survey and U.S.D.AjJjL 19 1966 



FOR IMMEDIATE RELEASE j|HN£RSHJMPi)i$, 1966 



INSECT SURVEY BULLETIN NO. 13 



This thirteenth weekly bulletin on the general insect situation in Illi- 

 nois (fruit insects excepted), prepared by entomologists of the University of Illi- 

 nois College of Agriculture, Illinois Natural History Survey and cooperating agen- 

 cies, reports general trends in insect activity and suggests abbreviated control 

 measures. Each individual should check his own fields to determine local condi- 

 tions. 



***** 



The most frequent question this week was what effect the hot weather might 

 have on insects. The heat has probably hurt the crops more than the bugs. However, 

 a siege of hot weather can cause insects to do strange things. To escape the heat 

 and sun, some species may seek shelter in places where they normally would not be. 

 So you can expect to find a few insects "out of place." For some species the op- 

 timum conditions for survival may have been greatly exceeded, and populations may 

 decrease to non-economic levels. But for some species the heat merely speeds up 

 body processes, adds a few extra generations to the normal annual number and thus 

 increases the insect problem. 



There is no "yes or no" answer to how hot weather affects insects. But 

 unfavorable growing conditions for crops tend to accentuate the damage caused by 

 insects. 



Fresent Farm Insect Problems 



European corn borer can be found in tne more mature fields of field corn 

 throughout the state, but only an occasional field has enough first-generation borers 

 to cause measurable damage. First-generation feeding may reduce yields in a few of 

 these fields by 2 to h percent, but most yields in fields we have investigated will 

 be cut no more than to 2 percent. 



Some moths have emerged as far north as a line from St. Louis to Lawrence- 

 ville. Pupation and moth emergence will progress northward until emergence begins 

 about August 5-10 in northern Illinois. 



We can anticipate three generations of corn borer in the southern 1/3 to 1/2 

 of the state this year, but only two generations in the remainder of the state. 



It would be useless to apply insecticides now in the northern half of Il- 

 linois for control of first generation. In southern Illinois, egg laying of second 

 generation may be starting now in fields in late whorl to early silk. Remember that 

 the moths will migrate from field to field. When a field becomes unfavorable for 

 egg laying, the moths search for a favorable one. 



Carbaryl (Sevin) or diazinon granules can be used to control corn borer. 

 Apply only if you find an average of one egg mass per plant when hatching has just 

 started. 



Chinch bugs can be found in small numbers on corn plants in a few border 

 rows of an occasional cornfield. No damage is anticipated. 



