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OR IMMEDIATE RELEASE July 8, i960 



INSECT SURVEY BULLETIN NO. 12 



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

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

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

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

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

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

 etermine local conditions. 



Corn borer : It is too late for the best results with insecticides in 

 Ilinois except in the northern two to three tiers of counties. Where needed, treat- 

 ents can still be applied in this area for the next few days. 



To determine need for treatment, examine 50 to 100 plants for signs of 

 orer feeding on the whorl leaves. If 75 percent or more of the plants show recent 

 horl feeding, check the tassel ratio. Measure from the base to the tip of the 

 lants with leaves extended. Split the plant lengthwise and measure from the base 

 f the plant to the tip of the developing tassel. Divide tassel height by plant 

 eight and multiply by 100. Take an average of five representative plants per field, 

 his is the tassel ratio. The corn will warrant treatment if the tassel ratio is 

 10 or above. Treatment after borers have drilled into the stalk proper will not be 

 ffective. 



DDT is still the insecticide most commonly used for corn borer. Apply 

 . 1/2 pounds per acre as a spray or 3/k to 1 pound per acre as granules. When 

 praying, arrange two or three nozzles over the row to cover the upper one- third of 

 ;he plants, particularly the whorl zone. Do not apply DDT to ensilage or stover to 

 •e fed to cattle. 



Chinch bugs ; There are a few isolated cases of chinch bug migrations 

 'rem small grain to corn. If control is necessary, apply 1/2 pound of dieldrin per 

 icre. If chinch bugs are still present in the small grain field, apply dieldrin 

 ;o a 2-rod strip into the grain field. Do not harvest the grain until 7 days after 

 ;reatment, and do not use the straw for feed until 30 days after treatment. 



Grasshoppers : Small 'hoppers are concentrated in fence rows, ditch banks, 

 roadsides and similar areas. Although luxuriant foliage in these areas may hold 

 ;he grasshoppers, they can be easily controlled now with l/h pound of dieldrin or 1 1/2 

 >ounds of toxaphene per acre. Do not graze dairy cattle on the sprayed areas. 



Stable flies ; These blood- sucking flies decrease milk production more 

 ;han any of the other flies. Since they breed in rotting straw and similar wet, 

 lecaying vegetation, we may expect a heavier than normal infestation this year. 

 Sprays of pyrethrins with either tabatrex or R-326 as repellents will prevent most 

 3f the losses caused by these pests. 



Face flies ; This new pest of cattle has increased slight^«^rlng the 

 ?ast two weeks and is expected to increase for the rest of the^usfler. At present, 

 bhe spray used for stable flies can be used for control. It should b^ usstrparticu- 

 Larly around the head, or as a smear on the head. A bait develop^&vby the Nad&ral 

 History Survey may soon have label clearance. ttf\\Y^ V> 



House flies ; This insect will multiply rapidly and become a nuisance if 

 the weather becomes warm. Practice good sanitation and follow with residual wall 



