X*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 May 6, 1966 



INSECT SURVEY BULLETIN NO. 3 



This third weekly bulletin of 1966 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 con- 

 trol measures. Each individual should check his own fields to determine local 

 conditions. 



Alfalfa weevils have seriously damaged alfalfa fields south of Highway 13- 

 Overwintering adults will continue to lay eggs, so populations of larvae can be ex- 

 pected to remain high during the next three weeks. It is too late to treat fields 

 where the terminal leaves and lower leaves of the plants are almost completely de- 

 stroyed. Cut the alfalfa and remove the hay, then immediately apply an insecticide 

 to protect the new growth. The sooner you remove the hay after cutting, the better 

 the weevil control will be. You will remove many eggs and kill many larvae. 



In the area between Highways 13 and 50, infestations are lower, and feed- 

 ing damage is not as noticeable. Each field must be rated on its own infestation. 

 Fields showing 75 percent or more terminal feeding should be treated immediately 

 if live larvae are present. Since serious damage can occur within a few days after the 

 75-percent feeding level is reached, treatment must be made promptly, but it may be 

 wiser at this stage of growth to cut the alfalfa a little earlier than normal, 

 remove the hay, and then treat the new growth. 



It is almost too late to apply parathion as most first-cutting alfalfa 

 is within 15 days of harvest. If temperatures are above 60° , use 1 pound of mala- 

 thion per acre or a commercially prepared diazinon-methoxychlor mixture. Use a 

 minimum of 10 gallons of water per acre when spraying by ground. No waiting pe- 

 riod is required between application of malathion and harvest. Allow one week to 

 elapse between application of diazinon-methoxychlor and harvest. 



For pastures, use malathion or the diazinon-methoxychlor mixture. You 

 can put animals right back on pastures sprayed with malathion, but wait one week 

 when using diazinon-methoxychlor sprays. 



This past week we visited experimental control plots at the University 

 of Kentucky. The weevils in the untreated areas had turned to alfalfa stems for 

 food as all the leaves had already been eaten. We are convinced that this pest will 

 be a serious alfalfa problem in Illinois. 



Alfalfa growers south of Highway 13 have seen severe damage this year. 

 Damage to alfalfa south of a line from St. Louis to Champaign will be severe and 

 general in 1967. 



Clo ver leaf we evils are green worms with white stripes down their backs. 



They resemble alfalfa weevils but have brown heads instead of black and are found 



in the soil debris during the day; alfalfa weevils are up on the plants during the 

 day. 



