6^a 



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 7, I965 



INSECT SURVEY BULLETIN NO. 3 



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

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

 versity of Illinois College of Agriculture, Illinois Natural History Survey and co- 

 operating agencies. It is designated 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. 



All stages of alfalfa weevils are now present in extreme southern Illinois. 

 Although some overwintering adults are still depositing eggs on alfalfa stems, larvae 

 are predominant in all fields and pupation is progressing rapidly. Spherical green, 

 silken pupal cases or cocoons can commonly be found; some are attached to leaves but 

 more are found in the crown or in ground debris. A few newly emerged adults are 

 also present. 



We are not recommending use of insecticides at this time. Even though we 

 have seen numerous fields where there has been considerable feeding, it is not se- 

 vere enough to warrant the cost of insecticides. How soon the alfalfa is to be cut 

 for hay is the important control factor. Harvesting of the hay crop will kill many 

 larvae if the sun is bright and hot. If the weather is cool and cloudy, the larvae 

 will be more likely to survive. Eggs now being deposited will probably end up in 

 bales in the barn where they will do little damage. Adults that emerge from this 

 generation will do little feeding and will be inactive throughout the summer. 



Heavily infested fields should be cut now. Larvae that survive cutting will 

 feed on the new shoots, so inspect new growth daily for several days after cutting. 

 If weevil larvae concentrate on this new growth and damage is severe, you may want to 

 apply one pound of diazinon or malathion per acre. Allow seven days to elapse between 

 treatment and harvest if diazinon is used; no interval is required with malathion., 

 Both malathion and diazinon will also control pea aphids. However, the need for an 

 insecticide application will be the exception rather than the rule. 



Alfalfa weevil has been found for the first time in Randolph, Monroe, 

 St. Clair, Clinton, Cumberland, Shelby, Douglas and Edgar counties. 



Pea aphid populations vary greatly from field to field, and many aphids are 

 being killed by wasp parasites. A disease is also killing aphids. Aphid predators, 

 such as larvae and adults of lady beetles, flower fly maggots and aphis lions, are 

 becoming numerous. No fields warranting insecticide treatment have been observed. 



Spotted alfalfa aphid is more common in southern and southwestern Illinois 

 this year than in past years but is not present in damaging numbers. Insect predators 

 of pea aphids feed on the spotted aphids, so the buildup of these predators will help 

 to control the spotted aphid. 



THE LIBRARY 8F. THE 



MAY 7 "coo 



