X n 7 



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 19, 1966 



INSECT SURVEY BULLETIN NO. 18 



This eighteenth weekly bulletin 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, 

 reports general trends in insect activity and suggests abbreviated control measures. 

 Each individual should check his own fields to determine local conditions. 



Corn leaf aphids have disappeared from most fields south of Highway 6 ex- 

 cept for an occasional field where, for some reason, numbers continue to hold up and 

 the aphids are transferring to the ear and lower part of the plant . Numbers in fields 

 north of Route 6 increased this past week but should decline this coming week. 



In general aphids this year have been most damaging in cornfields that have 

 been under various combinations of stress, such as extremely thick stands, drought 

 and weeds. Those fields with moisture available to the plants suffered the least 

 damage . 



Undoubtedly this will go down as the worst corn leaf aphid year on record. 

 Low populations of natural enemies, weather favorable for aphid survival, fertility 

 practices and perhaps other factors have contributed to this build-up. 



Corn rootworm beetles are increasing in abundance in cornfields, where they 

 are concentrating on the ears. In most fields, pollination has been completed and 

 silk feeding is not important, but the beetles are feeding on and damaging ear tips 

 slightly. Pollination in very late fields may be affected by silk feeding. Treat- 

 ment with insecticides at this time will not be profitable. Do not confuse these 

 green beetles with the small, wingless, soft -bodied green tarnished plant bug nymphs . 



Corn borer egg laying is progressing rapidly in northern Illinois. It 

 appears that second -generation numbers will not be much greater than in previous years . 



Two-spotted mites have been present on soybeans and are now present in num- 

 bers in some cornfields. Whether control would be profitable is open to question at 

 this late date. 



Many chemicals highly effective on mites are not approved for use on soy- 

 beans or corn. Carbophenothion (Trithion) can be used on beans at 3/^ pound per acre 

 to within 7 days of harvest, 1.0 pound of methyl parathion, can be used to within 20 

 days of harvest and l/2 pound of parathion to within 15 days of harvest. For corn 

 do not use carbophenothion more than once per season nor closer than 21 days of har- 

 vest or l/2 pound of parathion closer than 12 days of harvest. These chemicals should 

 be applied only by experienced operators. 



Grasshopper development is later than normal, and half -grown ones are still 

 present. However, only rarely would control pay because numbers are small. 



Homeowner's Insect Problems 



Leafhoppers are abundant around street lights and houselights. These 

 wedge-shaped insects may appear in swarms at night. Also, crickets are migrating 

 from pastures and wastelands and can be found around and in houses. 



<n 



