FOR IMMEDIATE RELEASE August 9, 1963 



INSECT SURVEY BULLETIN NO. 17 



This is the seventeenth in a series of weekly bulletins on the general in- 

 sect 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 measures. These reports 

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

 mine local conditions. 



Corn borer pupation of first generation, as expected, commonly has exceeded 

 90 percent. Emergence of moths from these pupae varies now from 60 to 90 percent. 

 Egg laying has reached its peak in western Illinois and should reach its peak in 

 northwestern Illinois this weekend, or at least during this coming week. From egg 

 counts, we believe that corn borer population will increase in the area from Quincy 

 to Peoria to Rockford. Also in this area, second generation damage will be quite 

 noticeable in the later field corn; this will be in the form of chaffy ears and dropped 

 ears at harvest. 



Grasshopper damage in some hay fields, particularly red clover, in northern 

 Illinois is noticeable. There are two species of grasshoppers present, the red legged 

 and the differential. Some of the red legged grasshoppers, the smaller of the two, 

 are now becoming adults and flying. Differential grasshoppers, the larger green or 

 yellow species, are still present as nymphs and will continue to feed for some time. 

 After grasshoppers become adults they concentrate on depositing their eggs in the soil 

 and do not eat as voraciously as when in the immature or nymph stage. 



For the most part, rains have supplied sufficient moisture for luxuriant 

 plant growth. This growth has supplied grasshoppers with enough food, so they have 

 not needed to migrate. Many are remaining in mowed hay fields, feeding on the tender 

 new growth. In a few instances, however, the grasshoppers have migrated to soybeans 

 and corn. 



To avoid killing pollinating insects when alfalfa or clovers are in bloom, 

 apply insecticides only in the late afternoon or early evening. If your sprayer has 

 been used for 2,4-L, clean it thoroughly before spraying legumes or soybeans. 



For pasture or hay crops, apply 3/^ pound of sevin, 1 pound of malathion or 

 3/^ pound of dibrom per acre. Sevin does not require any waiting period between ap- 

 plication and grazing or cutting for hay, but allow a 7-day interval with malathion 

 and a h~ day interval with dibrom. Diazinon at 1/2 pound per acre may be used only 

 on alfalfa, provided a 7-day waiting period is observed. For best results, apply in 

 the late afternoon. These four insecticides are the only ones recommended for hay 

 crops or pastures for dairy animals or livestock fattening for slaughter. 



Occasionally grasshoppers can be trapped into narrow, uncut strips of clover 

 cr alfalfa and then sprayed, reducing the overall cost of materials. Leave a few un- 

 cut swaths around the margin of the field and one swath a rod or so wide through the 

 center of the field. As you cut the remainder of the field, the 'hoppers will con- 

 centrate in these strips of uncut hay. Then spray the uncut strips. 



If areas will not be grazed or used for hay, apply 1 to 2 ounces iaf fl dleldrin 

 or 1 1/2 pounds of toxaphene per acre to control small 'hoppers. lonww Or IHt 



AUG l 2 1963 

 UNIVERSITY OF ILLINOIS 



