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INSECT 



SURVEY 



BULLETIN 



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State 



County 



Local Groups 



College of Agriculture 



University of Illinois 



and Natural History Survey, Urbana, Illinois 



S. Department of Agriculture Cooperating 

 THE LIBRARY OF THE 



FOR IMMEDIATE RELEASE 



APR 26 1967 



MUVERSH OF ILLINOIS 



INSECT SURVEY BULLETIN NO. 2 



April 21, 1967 



This series of weekly bulletins provides a general look at the insect situation 

 (fruit insects excepted) along with suggested, abbreviated control measures. Each 

 individual should check his own fields to determine local conditions. 



Alfalfa weevil populations are high in most alfalfa fields south of Highway 40. 

 In the area between Highway 40 and a line from Champaign to Pittsfield, larvae 

 can be found, and feeding is noticeable in some fields. Occasional fields in this 

 area may need treatment in the next week or two. 



In the area south of Highway 40, larvae are pupating (resting stage), but eggs are 

 still being laid so that populations of larvae remain high. The situation will 

 probably remain critical until the middle to latter part of May. In the southern 

 two to three tiers of counties, new spring adults are emerging in large numbers. 

 These adults will feed for awhile on the alfalfa, move to wooded areas (often some 

 distance away), and then remain quiet through the summer. In the fall, they will 

 become active and deposit some eggs before hibernating for the winter. 



Weevil populations and damage vary considerably from field to field, and each field 

 should be judged on an individual basis. In some fields, the alfalfa has already 

 been completely destroyed. It is too late to treat fields where the leaves are 

 almost completely destroyed. Cut the alfalfa and rake off the stems, then spray 

 with an insecticide to protect the new growth. 



In general, treatments are being applied too late for maximum benefit. When 25 to 

 50 percent of the terminals show apparent feeding and larvae are still present, 

 fields should be treated immediately. Serious injury can occur within a few days 

 after this feeding level is reached. Some fields will need retreatment in two or 

 three weeks, but by that time, it may be wiser to cut the alfalfa, remove the hay, 

 and then treat the new growth. 



It is now apparent that in the area south of Highway 15, three treatments will be 

 needed in most fields to adequately protect the alfalfa. The second treatment is 

 already due. In the area between Highway 15 and 40, two treatments will be needed 

 in most fields to give satisfactory protection. 



Plan on applying 20 gallons of water per acre with the correct amount of insecti- 

 cide, except for stubble sprays where 10 to 12 gallons per acre is adequate for 

 coverage. We have observed good results with aerial applications, using 4 gallons 

 of finished spray per acre. 



