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FOR IMMEDIATE RELEASE July 10, 196h 



INSECT SURVEY BULLETIN NO. 13 



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This is the thirteenth in a series of weekly bulletins 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. It is designed to forewarn people in Illinois 

 of impending changes in insect activity and to suggest abbreviated control meas- 

 ures. These reports indicate only general trends. Each individual should check 

 his own fields to determine local conditions. 



Fall armyworms and yellow- striped armyworms , not true armyworms, are 

 present in small numbers in late-planted corn. The fall armyworm is gray to 

 brown, while the yellow- striped armyworm is velvety brown to black with a promi- 

 nent yellow stripe along both sides of the back. These worms feed in the whorl, 

 and the plants develop a ragged appearance as leaves emerge. There are usually 

 several infested plants in a row, since the worms move out in both directions 

 from the plant on which the eggs are hatched. Populations of these insects will 

 probably continue to increase from now until September in late-maturing corn. 



If 20 percent or more of the plants are infested, treatment may be 

 profitable. Use 1 if 2 pounds of DPT, carbaryl (Sevin) or toxaphene per acre. 

 Granular insecticides will penetrate the whorl more readily than sprays and pro- 

 vide better control. Do not use DDT or toxaphene if the corn is to be used as 

 ensilage or stover for dairy cattle or animals being finished for slaughter. 



Two- spotted mites are damaging fields of soybeans that border clover 

 fields. When the clover is cut for hay, the mites move into the soybeans and 

 begin feeding. The damage appears as a brown speckling of the leaves. When 

 beans are severely infested, webbing is noticeable. However, the tiny mites, 

 which like the undersides of the leaves, are difficult to see unless the leaves 

 are jarred over a white paper or cloth. Dry weather favors mite development, 

 while moisture discourages mite build-up. 



Control measures, in general, have been inadequate. If damage is 

 severe, try a malathion spray at 1 pound per acre in as much water as possible, 

 directed at the undersides of the leaves from drop nozzles. Do not harvest as 

 forage or feed until three days after treatment. 



Potato leafhoppers are causing yellowing of second- cutting alfalfa. 

 These tiny green, wedge-shaped insects suck sap from alfalfa plants, causing yel- 

 lowing or purpling and stunting. The damage lowers both quality and quantity of 

 the hay. If this pest is abundant or yellowing is occurring, apply 1 pound of 

 methoxychlor or carbaryl per acre. Allow one week to elapse between application 

 of methoxychlor and harvesting or pasturing. There is no waiting period when 

 carbaryl is used. 



Note to Sweet Corn Producers 



Corn sap beetles are now appearing in corn. They are feeding on fer- 

 menting pollen and in earworm and corn borer galleriesJ(j'(Grpwers^of market sweet 

 corn and canning sweet corn should watch for these beetles arid should treat if 

 they are abundant. Treatment should be applied before^'the- beetle^ lay eggs in 

 the silk channels. For control, use diazinon or malathion and observe label 

 precautions. 



Corn earworm moths are being caught daily in moderate numbers in the 

 light trap at Urbana. 



