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known as the spotted cucumber beetle. Western corn rootworms were found for the first 

 time in Christian and Menard Counties this week. Confirmed findings have been made in 

 forty-nine counties in the northern half of Illinois. If the western corn rootworm ha 

 not been reported in your county, please take suspected beetles to your county Extensii 

 adviser, or send them to Extension Entomology, 280 Natural Resources Building, Urbana, 

 Illinois 61801. 



Fall armyworms . This pest is damaging late-maturing corn, particularly in the south- 

 ern sections of the state. These dark-brown to gray to dull-green, smooth- skinned 

 worms feed in the whorl, giving the plants a ragged appearance as the leaves emerge. 

 A series of plants in a row will show damage, and these patches of infested plants 

 will usually be over the entire field. The worms this week were a third to half 

 grown, with another 7 to 10 days of feeding time left before they mature. Addition- 

 al generations could still present further problems in late-maturing fields. After 

 the corn has pollinated, fall armyworms will attack the developing ears (like ear- 

 worms) . Some larvae will be present in ears until frost. 



Treatment is justified in fields in which 20 percent or more of the plants are in- 

 fested. Before applying insecticides, be sure the worms are still present and that 

 most of them are not more than 1-1/4 inches long. When they reach about 1-1/2 inches, 1 

 they are mature; at that size they stop feeding, drop to the ground, enter the soil, 



and pupate. M 



i 



For control, apply either carbaryl (Sevin) , Gardona, and toxaphene at 1-1/2 pounds of, 

 chemical per acre, or diazinon at 1 pound per acre. Granules are preferred, especiall 

 if air applications are made. Ground applications with the spray directed into the 

 whorl will provide fair to good results, depending on the size of the worms. The 

 larger worms that are deep in the whorl are more difficult to reach with an insecti- ; 

 cide, and control is poor. Smaller worms, many of which are on exposed leaves, are 

 readily killed. 



Do not feed toxaphene- treated corn as forage to dairy cattle. Do not feed toxaphene- , 

 treated corn as silage to livestock fattening for slaughter. Corn treated with toxa- , 

 phene granules may be fed as stover to beef cattle to within 28 days of slaughter. 

 There are no restrictions for carbaryl. For diazinon, there is a 10-day waiting per- 

 iod between application and removal of forage, and 7 days for grain; for Gardona, 

 there is a 5-day waiting period between application and removal of forage and grain. 



Caterpillars . An orange and brown, bristly caterpillar (Simyva henrioi) can be found 

 in some corn fields, eating the edges of the leaves. There is no common name for this 

 worm. Control is not necessary. 



Picnic beetles . There are not as many of these in cornfields this year as last year. 

 A cool, wet spring is usually associated with an abundance of this species. They over 

 winter as adults and larvae. Being scavengers, they develop on fallen ears and other 

 organic matter. Occasionally, beetles feed on the silks and the tips of the ears. Thi 

 usually shows up after pollination has occurred. Control is rarely needed. 



SORGHUM INSECTS 



Sorghum midge . Damage to sorghum by this insect has been reported in southern Illi- 

 nois. Injury is caused by tiny maggots feeding inside the seed. If the infestation 

 is severe, the heads appear blasted or blighted, and will produce little or no grain. 



Damage can only be prevented by controlling the adult midge before the eggs are de- 

 posited. Thus, control requires precise timing of insecticide applications. The 



