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CORN INSECTS 



The second generation of European corn borers may be more numerous this year than for 

 several recent ones. Although the first-generation borers required chemical control 

 in only a few fields , a large number of fields did have some borers . This adds up to 

 a big supply of moths which will be laying eggs in the fields planted later. Our first 

 generation survey, just begun, shows higher populations in southern, southwestern, and 

 western Illinois than in eastern and parts of central Illinois. 



In the southern and southwestern sections, over 60 epercent of the first-generation 

 borers have already pupated. About 10 percent have emerged as moths. Egg- laying has 

 started and will continue for three weeks or more. Examine fields in the late-whorl 

 to early silk stages for egg-laying. 



In west- southwestern and western Illinois, about 25 percent of the first-generation 

 borers have pupated, and 3 percent have emerged. Expect egg- laying to be well underway 

 within ten days. 



In northern Illinois, 10 to 20 percent of the first-generation borers have pupated. No 

 moths have emerged yet. Egg- laying will start in about ten days. 



If fields average one egg mass per plant, apply chemical control when eggs have begun 

 to hatch. Carbaryl (Sevin) and diazinon are recommended. Do not apply within ten 

 days of harvest. 



In years past, corn borers have been infected by a microscopic protozoan animal that 

 is transmitted from generation to generation. The borers that lived through this past 

 winter were moderately infected. Thus, we may get some help from this form of natural 

 control. We will be checking borers for this disease during the coming week. 



Corn rootworm beetles will be very numerous in some fields in about 10 days to two 

 weeks. Rootworm beetles feed on the silks. If this takes place after pollination, 

 little harm is done. If it occurs during or before pollination, yields can be greatly 

 reduced. Check late-maturing fields frequently during pollination. Keep them under 

 observation until pollination is about complete. 



As a guide, we suggest chemical control if the corn is less than 50 percent pollinated 

 and you find five or more beetles per plant . Apply 1 pound of carbaryl (Sevin) , mala- 

 thion, or diazinon per acre. Do not harvest for 10 days when using diazinon, or 7 days 

 for malathion. Since these beetles are killed easily, other insecticides may be effec- 

 tive. 



Woolly bears and cattail caterpillars (brown, orange- striped, and bristly) are present 

 in corn fields. The woolly bears like to feed on the silks, the cattail caterpillar 

 on the leaves. Insecticide control is seldom needed. 



SORGHUM INSECTS 



Corn leaf aphids are extremely abundant. Most sorghum insect authorities to the south 

 and west of Illinois say that corn leaf aphid feeding, although severe, rarely inter- 

 feres with yields. These aphids will suddenly begin to disappear just before the sor- 

 ghum heads. However, it is difficult to sit idly by when aphids are matted on the 

 leaves and the upper leaves are turning brown. 



For control, apply 1 pound of malathion or 1/2 pound of diazinon per acre. Do not ap- 

 ply within seven days of harvest. 



