

FOR IMMEDIATE RELEASE 



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INSECT 



SURVEY 



BULLETIN 



College of Agriculture 



University of Illinois 



and Natural History Survey, Urbana, Illinois 



THE UDilAnV OF THt 



S. Department of Agriculture Cooperating 



M AY 1 i 1967 



UMVERSIY OF ILLINOIS 



INSECT SURVEY BULLETIN NO. 5 



May 12, 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. 



Forage Insects 



The alfalfa weevil feeding has slowed to some extent with the cool temperatures, 

 but not enough to alleviate the problem. Economic damage is still occurring in 

 most alfalfa fields south of a line from Paris to Alton. However, populations 

 are still expected to be damaging for another two to four weeks in this area. It 

 appears that the peak has been reached and populations are now beginning to decline 

 in southern sections. North of this line (Paris to Alton), weevil feeding is no- 

 ticeable, but not of economic importance. 



Many larvae are now pupating; new spring adults are already abundant, particularly 

 in southern sections. These adults will feed for awhile on the alfalfa, move to 

 wooded areas, and then remain quiet through the summer. In the fall, they will 

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

 ing damage appears as a feathering of the leaf margins (see picture) , in contrast 



to the skeletonizing injury of the larvae. 



There is no satisfactory control available for 



adult alfalfa weevils . 



In most of the current problem fields, it would 

 be best to cut the alfalfa if flower buds are 

 showing, remove the hay, and spray the new 

 growth of the second crop. If the crop has 

 been cut, but the new growth of the second crop 

 not sprayed, watch it closely for evidence of 

 weevil damage. If it does not green-up in 

 two or three days and worms are present, treat 

 it promptly. Other fields should be treated 

 immediately when 25 to 50 percent of the ter- 

 minals show apparent feeding and larvae are 

 still present. 



For control of alfalfa-weevil larvae, farmers making their own applications should 

 use either malathion or a commercially prepared methoxychlor-diazinon (Alfatox) 

 mixture. Commercial applicators can use either of the above materials or one of 

 the more toxic insecticides like methyl parathion or azinphosmethyl (Guthion) . Be 

 sure and follow label directions for dosages, harvest limitations, and precautions 

 when using insecticides . 





Damage by adult alfalfa weevil 

 (feathering of leaf margins) 



