XV, / 



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 13, 1966 



INSECT SURVEY BULLETIN NO. k 



This fourth 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. 



The Present Farm Insect Problems 



Alfalfa weevil feeding may have been slowed down a little by cold weather 

 and the cold snap may have killed some larvae, but it was not enough to alleviate the 

 weevil problem. 



Many larvae are now pupating, and some new adults have already emerged in 

 southern Illinois. They will feed on the alfalfa for a week or two and then remain 

 quiet during the heat of summer; in the fall they will become active and deposit 

 some eggs before winter hibernation. Next March they will come out of hibernation, 

 feed, and lay eggs. 



This year it is already too late to save the first cutting in heavily in- 

 fested fields south of Route 13. Here, cut the hay, remove it, and immediately spray 

 to protect the second growth. 



This week we saw economic damage as far north as Robinson on the east to 

 Clinton County (Carlisle) on the west. North of this line, weevil feeding is notice- 

 able but not of economic importance. 



If 75 percent of the terminals show evidence of feeding, you may still want 

 to apply an insecticide, but applications should be made right now. 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 mini- 

 mum of 10 gallons of water per acre when spraying by ground. No waiting perioc is 

 required between application of malathion and harvest. Allow one week to elapse be- 

 tween application of diazinon-methoxychlor and harvest. For pastures, use malathion 

 or the diazinon-methoxychlor mixture. 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 para- 

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

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



Pea aphid numbers in alfalfa fields remained low this week. 



English grain aphids are reported to be abundant on the undersides of wheat 

 leaves. No control need be applied unless the plants show wilting. After wheat 

 heads appear, it takes an average of 30 to 50 aphids per head to cause measurable 

 damage. Ordinarily the aphids will leave the wheat head as it enters the dough stage. 

 If control is absolutely necessary, use one pound of malathion per acre. Although you 

 can apply malathion to within one week of harvest, that would be far too late for 

 profitable control of grain aphid. Operators equipped with protective clothing can 

 a PPly one-fourth pound of parathion to within 15 days of harvest. 



