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INSECT 



SURVEY 



BULLETIN 



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College of Agriculture 



University of Illinois 



and Natural History Survey, Urbana, Illinois 



U. S. Department of Agriculture Cooperating 



FOR IMMEDIATE RELEASE 



March 29, 1968 



INSECT SURVEY BULLETIN NO. 5 



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. Before ap- 

 plying insecticides, read the labels carefully and follow all precautions. This 

 will not only insure personal safety, but will also prevent residue hazards. 



Alfalfa weevil larvae are now hatching in southern Illinois. The coming of warmer 

 weather has increased egg hatch and egg laying, resulting in a buildup in the num- 

 ber of larvae; also, the alfalfa is beginning to grow. Check the alfalfa fields 

 closely for damage caused by the larvae feeding on the terminal leaves . 



In the new plant growth, newly-hatched larvae feed within the growing plant tips 

 and on the upper leaves as they open. They skeletonize the leaves, which then 

 dry rapidly. Severely damaged fields take on a grayish to whitish cast. 



If you intend to protect your alfalfa from weevil attack, begin to make prepara- 

 tions now. The first insecticide applications will probably not be needed in more 

 advanced fields in extreme southern Illinois until the first week in April or later, 

 depending on the weather. A spot check of alfalfa tips will give you some indica- 

 tion of damage. Select 25 terminal tips at random, and carefully examine them for 

 the presence of small larvae or feeding injury. 



Apply the insecticide when weevil feeding has become noticeably apparent on 25 

 percent or more of the terminals. Newly-hatched larvae are about 1/20 of an inch 

 long and are yellow, except for a shiny black head. When full grown, they are 

 about 5/8 of an inch long, green, with a wide white stripe running down the middle 

 of the back. 



The recommendations are: 



1. Experienced commercial applicators who have the proper protective clothing 

 will get best results with methyl parathion applied at 1/2 pound per acre or 

 a special alfalfa weevil spray of azinphosmethyl (Guthion) at 1/2 pound per 

 acre. Azinphosmethyl can be applied only once per cutting. 



2. The person not properly equipped with protective clothing to use methyl para - 

 thion or azinphosmethyl can use a mixture of 5/4 pound of malathion and 5/4 

 pound of methoxychlor per acre or a mixture of 1/2 pound of diazinon and 1 

 pound of methoxychlor per acre. When air temperatures are above 60° F. , you 

 may also use 1 1/4 pounds of malathion per acre. 



bltliVEUSITY OF ILLINOIS 



APR -9 1968 

 LIBRARY 



