It would be useless to apply insecticides now for the control of first-generation 

 corn borer , even in the northern sections. Some second-generation corn borer 

 moths are emerging in the southern sections; pupation is just beginning in the 

 northern sections. We can expect a third generation in southern sections, but 

 only two generations in the remainder of the state. 



Peak egg laying will probably occur the week of July 23 in southern sections, the 

 first week of August in central sections, and the second week of August in northern 

 sections . Moth emergence will probably extend over a longer period than for the 

 first generation, and we could have a prolonged egg-laying period (3 to 4 weeks) . 



Damage from second-generation corn borers could be severe, and the moths will tend 

 to concentrate their egg laying in fields in the late-whorl to early-silk stage. 

 The moths will migrate readily from field to field. 



Carbaryl (Sevin) or diazinon as granules or sprays are effective against second- 

 generation corn borers. Apply at first hatch if there is an average of one or 

 more egg masses per plant. 



Northern corn rootworm larvae can still be found feeding on corn roots. They are 

 from 1 to 2 weeks behind in their development, compared to last year. About 10 

 percent of the larvae have pupated in central sections; pupation is just beginning 

 in northern sections. A few adult beetles should appear about 10 days from now. 

 Adult western corn rootworms should appear at about this same time in the limited 

 area of infestation in the western section. Reports of rootworm damage to corn 

 treated with aldrin or heptachlor continue to filter in. Last year approximately 

 10 percent of the cornfields in the northern half of the state had resistant 

 beetles. The resistance problem is obviously increasing again this year. 



It is now too late to apply control measures for the larvae. Control of adult 

 beetles that feed on silk may be needed to prevent injury to pollination in early 

 to mid-August. 



Armyworms are present in small numbers in occasional fields of grassy corn in 

 northern sections. If needed, carbaryl (Sevin) at 1 1/2 pounds per acre as a 

 spray will give adequate control. Toxaphene at 1 1/2 pounds per acre can also be 

 used- -but only on corn grown for grain, not on ensilage corn. 



Corn blotch leaf miners were reported heavy, especially on the lower leaves, in 

 one field this week. The insect is common in many fields, but the mines seldom 

 cover a large portion of the leaf; only a few leaves per plant are involved. 

 The green-to-white nearly transparent maggot (1/4-inch long) tunnels between the 

 leaf tissues, leaving transparent galleries that appear as white-to-gray blotches. 

 The damage done by this insect is believed to be of little economic importance. 

 No effective control is known. 



iVooly bears and cattail caterpillars (brown, orange- striped and bristly) are pres- 

 ent in cornfields"! The wooly bears like to feed on silks, the cattail caterpillar 

 on leaves. Insecticide control has seldom been needed for these insects. 



Soybean Insects 



Green cloverworms and cabbage loopers are feeding on soybeans in the southern sec- 

 tions . Damage is not apparent as yet, but the situation bears watching. 



