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INSECT 



SURVEY 



BULLETIN 



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College of Agriculture 



University of Illinois 



and Natural History Survey, Urbana, Illinois 



State / County / Local Groups / U. S. Department of Agriculture Cooperating 





FOR IMMEDIATE RELEASE 



INSECT SURVEY BULLETIN NO. 4, 





May 5, 1967 



'ft. 



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 continues to hold the spotlight. Economic damage is occurring 

 in most alfalfa fields south of a line from Paris to Alton. North of this line, 

 weevil feeding is noticeable, but is not of economic importance as yet. 



In the area south of Highway 13, larval populations continue at the same high peak 

 they reached a month ago. In this area, populations should begin to decline in a 

 week or two, as egg laying slows and larvae continue to pupate. In the meantime, 

 many fields are already overdue for their second treatment. In addition to tip 

 feeding, larvae are also feeding on the new crown shoots. 



In most of the 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. Other- 

 wise, fields should be treated immediately when 25 to 50 percent of the terminals 

 show apparent feeding and larvae are still present. Malathion is the preferred 

 material to use when treating close to harvest, since no waiting period is required. 

 However, malathion performed poorly during the cool weather this past week. 



Plan on applying 20 gallons of water per acre with the correct amount of insecti- 

 cide, except for stubble sprays where 10 to 12 gallons per acre is adequate for 

 coverage. We have observed good results with aerial applications, using 4 gallons 

 of finished spray per acre. Rain- -especially right after spraying- -may reduce ef- 

 fectiveness, requiring a repeat treatment. 



The following insecticides are suggested for alfalfa weevil control: 



1. Methoxychlor, 1 pound, plus diazinon, 1/2 pound (Alfatox) per acre . Effective 

 for approximately 10 to 14 days. Do not harvest for 7 days after treatment . 



2. Malathion, 1 pound per acre . Effective for approximately 3 to 7 days. Do no t 

 apply if air temperature is below 60° F .; failure may result. There is no 

 waiting period between treatment and harvest, making this an ideal choice for 

 pasture treatment. 



3. Methoxychlor, 1 pound per acre . Effective for approximately 5 to 8 days. Do 

 not harvest for 7 days after treatment. Results from Dr. Ed Armbrust's research 

 plots show methoxychlor to be less effective than malathion or Alfatox. 



