_^ ^ Cooperative Extension Service 



-*--^ Kl - ' University of Illinois College of Agriculture 



in Cooperation With the Illinois Natural 



History Survey and U.S.D.A. ffifflZZTi (i£ Nil 



FOR IMMEDIATE RELEASE July 16, 1965 



INSECT SURVEY BULLETIN NO. 13 



This is the thirteenth 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. 



Chinch bug migrations, except in a few instances, are complete. Adults 

 will now be flying in search of suitable corn, sorghum or grass fields where they 

 will deposit eggs for another generation of bugs. They will concentrate on thin, 

 weak spots in these fields. This next generation will be noticeable in two to 

 three weeks. For control, apply 1 l/k pounds of carbaryl (Sevin) per acre. This 

 can be used on sorghum, corn or grass for forage with no interval between appli- 

 cation and harvest. Allow 21 days between application andharvest of sorghum as grain. 



Corn borer moths are depositing eggs in the southern part of Illinois, 

 but most of this activity is confined to the southern tip. Here egg masses will 

 be concentrated on corn in the pretassel to early silk stage. 



No moth emergence has been noted this week in the northern half of Illi- 

 nois but pupation has begun throughout most of this area. Thus a few moths will 

 be flying and laying eggs in about two weeks. 



Corn borers are being killed or driven from their burrows by scavenger 

 beetles. This is further decreasing the borer population. At present, we do not 

 anticipate a severe second generation corn borer infestation. 



Salt-marsh caterpillars , generally called woolly bears, have been very 

 abundant in some cornfields of central Illinois. They have fed on the corn leaves 

 and silks. Less than 5 percent of the silks have been fed upon in the infested 

 fields and in general, the silks will grow back and be pollinated. Silk recovery 

 will not be complete but will be nearly so. It is doubtful that chemical control 

 will be required. 



Northern corn rootworms , as previously reported, have been damaging in 

 some fields of continuous corn where a soil insecticide, either aldrin or heptachlor 

 has been used for several years. This is resistance as discussed for the past 

 three years. Even in northern Illinois, populations this week varied from mature 

 worms to adults so applications of insecticide now would be of no value so far as 

 root damage is concerned. 



Corn leaf aphids have begun to build-up in the southern part of Illinois 

 and will soon appear in central Illinois. We cannot recommend a control for this 

 pest as we do not know the best timing for an insecticide application to receive 

 maximum benefit s . 



