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FOR IMMEDIATE RELEASE June 10, i960 



INSECT SURVEY BULLETIN NO. 8 



This is the eighth in a series of weekly bulletins on the general insect 

 situation in Illinois (fruit insects excepted), prepared by entomologists of the 

 Illinois Natural History Survey, University of Illinois College of Agriculture and 

 cooperating agencies. It is designed to forewarn people in Illinois of impending 

 changes in insect activity and to suggest abbreviated control measures. These re- 

 ports indicate only general trends. Each individual should check his own fields to 

 determine local conditions. 



Corn borer ; Pupation of overwintering borers is complete throughout the 

 state. Emergence is complete, or nearly so, in southern Illinois, and egg-laying 

 is practically complete. 



Emergence in central Illinois between Highway 36 and Highway 6 varies from 

 75$ in the west and south to 25$ in the north and east. In this area peak moth 

 flight will range from June 10 to 25, with peak egg-laying and hatch from June 15 

 to 30. Where needed on field corn, insecticides probably should be applied between 

 June 20 in the southwestern part of this area and early July in the northeastern 

 part. 



Emergence in the area north of Highway 6 varies from to 25$. Peak moth 

 flight is expected June 15 to 30, with peak egg-laying between June 20 and early 

 July. Where needed on field corn, insecticides probably should be applied in the 

 last few days of June and early July. 



The above dates are approximations and may vary a few days, depending upon 

 weather conditions. In general, most advanced fields in the area north of a line 

 from St. Louis to Kankakee should be checked every few days during the period of 

 egg-laying. Egg-laying this year could very well be concentrated in about 5$ of 

 the corn crop. 



DDT is still the generally recommended insecticide at 1 1/2 pounds per 

 acre in the form of granules or sprays. It is usually not profitable to apply 

 insecticides to corn for ensilage purposes; but if it is to be treated, endrin is 

 recommended in' place of DDT. 



Armyworms : These insects have appeared in rank growth of wheat in south- 

 western and western Illinois. They have been controlled readily with l/k pound of 

 dieldrin or 1 1/2 pounds of toxaphene; either one does a good job, but results are 

 not complete until h days after treatment. Do not harvest grain until 7 days after 

 treatment. 



Black cutworms : A few reports of these pests have been received. Low 

 spots in corn fields are usually attacked first; then the worms migrate out of these 

 spots, cutting corn as they go. Apply l/2 pound of dieldrin, 1/k pound of endrin, 

 or 3 pounds of toxaphene per acre when damage first appears and before worms are 

 full-grown. To insure the quickest and best kill, direct the spray at the base of 

 the plants onto the soil, and use as much water per acre as possible. Immediate 

 cultivation, throwing dirt around the plants, will also help in control. 



Other corn soil insects : Grape colaspis , tiny white worms that feed on 

 the root hairs of corn and soybeans following clover or two years of soybeans, are 

 appearing in central and south-central Illinois. Plants are stunted*j,turnppur£le, 

 or yellow and may die. The worm is white, grub- shaped and about the'sl2e or a 

 large comma. Early-planted fields are usually damaged more than the Later ^plan^ejl 



UNIVERSITY OF ILLINH^ 



