-i-sHr f 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 August 20, 1965 



INSECT SURVEY BULLETIN NO. 18 

 (FINAL ISSUE) 



This is the eighteenth and final issue in a series of weekly bulletins on 

 the general insect situation in Illinois (fruit insects excepted), prepared by ento- 

 mologists of the University of Illinois College of Agriculture, Illinois Natural His- 

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

 of impending changes in insect activity and to suggest abbreviated control measures. 

 These reports indicate only general trends. Each individual should check his own 

 fields to determine local conditions. 



Corn leaf aphids are being killed by parasites, predators and disease. 

 Fields observed this week showed from 20 to 90 percent mortality of aphid populations. 

 Insecticide treatments will no longer be needed to control this pest. 



Chinch bugs were observed damaging spots in cornfields and may also be nu- 

 merous in such grasses as millet, sudan and sudan-sorghum crosses in eastern Illinois. 

 Most of them are second-generation nymphs, but some first -generation adults are still 

 present. Carbaryl at 1 l/k pounds per acre has proved effective against chinch bugs. 



Fall armyworm damage is now evident in many late -maturing cornfields. Some 

 fields of corn still in the whorl stage or just now tasseling showed 70 to 80 per- 

 cent feeding damage. However, many of the worms are full grown (l l/k inch) or have 

 already left the plant to pupate in the soil. 



Unless at least 20 to 25 percent of the plants still have worms less than 

 one inch long, treatment is not justified in field corn. Carbaryl or diazinon as 

 granules will provide control. Allow two days to elapse between treatment with diazi- 

 non and harvest of the corn for ensilage, stover or grain. Carbaryl has no waiting 

 period. 



Corn borer moth emergence is complete in the central and western sections 

 and is nearing completion in the northern section of Illinois. Egg laying will con- 

 tinue for another two or three weeks, but we do not expect severe corn borer damage. 



Occasional fields of late -maturing corn may be damaged, since moths will 

 concentrate their egg laying here. Fields a-veraging one egg mass or more per plant 

 can be profitably treated at first hatch with either carbaryl (Sevin) or diazinon as 

 granules. 



Special Note to Seed Producers : Corn earworms are now hatching in many 

 cornfields in central and northern Illinois. Moth egg -laying activity has increased 

 this past week, but the overall infestation should be less than that of last year. 

 These second -generation worms are hatching from eggs laid on the silks. Seed pro- 

 ducers may wish to protect their late -maturing fields with sprays or dusts of DDT or 

 carbaryl. Make the first application when the field is in full silk, and treat again 

 seven days later for best results. Some fall armyworm and corn borer are also in ear 

 tips. 



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