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 20, 1966 



INSECT SURVEY BULLETIN NO . 5 



This fifth weekly "bulletin 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 control measures. 

 Each individual should check his own fields to determine local conditions. 



Present Farm Insect Problems 



Alfalfa weevil larvae have reached their peak and are now pupating 

 rapidly; some adults have already emerged. Although these adults will feed, they 

 will not lay eggs until this fall or next spring. Oddly enough, some of the old 

 overwintering adults are still depositing eggs, and newly hatched larvae can be 

 found. We will therefore continue to see some green larvae on alfalfa for another 

 three weeks . 



Many fields of alfalfa south of Highway 13 were protected with malathion 

 sprays. Where no insecticide was applied to the first growth, yields were very 

 low. However, in some of these fields malathion was applied as soon as the first 

 cutting was removed. Results appear to be good, and the plants are growing rap- 

 idly, if malathion was applied when temperatures were below 60 , inspect care- 

 fully to be sure that enough weevils were killed to protect the new growth. Sec- 

 ond growth, if not treated, may he seriously damaged; treat if new growth is being 

 devoured . 



The situation is spotted in the area north of Highway 13 to a line from 

 Robinson west to about St. Louis. Some fields should already have been treated, 

 but weevil feeding is just now approaching the peak. Some fields will still profit 

 from an insecticide application. 



If 75 percent of the terminals show evidence of feeding, apply an insec- 

 ticide. If you do not apply one immediately, harvest the crop a little earlier than 

 normally; remove the hay and then protect the new growth with an insecticide. 



For first growth, use one pound of malathion per acre or a commercially 

 prepared diazinon-methoxychlor mixture when temperatures are above 60 , Use a 

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

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

 elapse between application of diazinon-methoxychlor mixture and harvest. You can 

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

 using diazinon-methoxychlor sprays. 



After the first cutting is removed, azinphosmethyl (Guthion), methyl 

 parathion or parathion can be applied by those equipped to follow safety precautions 

 in handling these materials. Malathion and diazinon-methoxychlor may also be used. 



