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INSECT 



SURVEY 



BULLETIN 



ABWfe, 



ate / County / Local Groups 



College of Agriculture 



University of Illinois 



and Natural History Survey, Urbanar l)tocus 



U. S. Department of Agriculture Cooperating 



FOR IMMEDIATE RELEASE 



April 26, 1968 



INSECT SURVEY BULLETIN NO. 7 



This series of weekly bulletins provides a general look at the pest situation 

 (fruit and commercial vegetables excepted) } along with suggested, abbreviated con- 

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

 conditions . The plant disease report was prepared by the Department of Plant 

 Pathology , the insect situation report by the Department of Agricultural Entomol- 

 ogy and the Illinois Natural History Survey. 



FIELD CROP PEST PROBLEMS 



Forage Crops 



Alfalfa weevil development almost came to a standstill during this past week. Egg- 

 laying by the adults has been slowed down by the cool weather, and feeding has been 

 greatly reduced. Larval populations could have exploded this week in much of the 

 alfalfa weevil area; actually, there was a noticeable increase of larvae in some 

 areas, but not in the proportions expected. 



Adults are quite numerous in alfalfa fields now. When brought inside, these adults 

 immediately begin to deposit eggs in quantities. Thus, as soon as the weather 

 warms up, we can expect a surge of egg-laying, which will be followed within 10 days 

 by severe weevil feeding. 



This delay of weevil development could prove to be beneficial. Many eggs may be 

 removed from fields as the hay is harvested; also, many small worms will be either 

 removed or killed by exposure to the sun. On the other hand, if the alfalfa is 

 cut before or during this siege of egg- laying, eggs will be deposited on the second 

 growth, resulting in severe damage to that growth. 



However, the entire situation is so erratic that no general rules that would apply 

 to all fields can be given. Each field has to be judged by itself. Take into 

 account the abundance of weevil larvae, terminal feeding, alfalfa growth, and 

 length of time until harvest. Some fields may escape injury, while others may 

 be severely damaged; the temperature of the next few weeks will be the determining 

 factor. But in many fields, the alfalfa is now ahead of the weevil, and may con- 

 tinue to outgrow the feeding of these insects. 



In the area south of a line from Harrisburg to Carbondale, fields already sprayed 

 may be ready for a second treatment by the week of April 29. Some fields that 

 have not been treated are showing noticeable damage, which will increase. Fields 



