-2- 



sufficient eggs to cause economic problems in 1969, if the field is planted to 

 corn again. However, it is possible that two or more applications may kill 

 enough adults now to reduce the number of larvae next year. 



European corn borer moths seem to be abundant in some areas of north-central 

 Illinois; this indicates a greater potential second-generation population than 

 previously expected. In northern sections, about 70 percent of the second- 

 generation moths had already emerged this week. Egg-laying will continue in the 

 central section for another week or two, and in northern sections for another 

 2 to 3 weeks. Late-maturing fields should be checked for the presence of the 

 borer eggs. An average of 1 egg mass or more per plant is sufficient to justify 

 an insecticide treatment. Make the application at first egg hatch. 



SOYBEAN INSECTS 



Green cloverworms are being killed by a fungus disease and parasitic flies. Worms, 

 dead from disease, are white to tan, and the body tissues are hard (mumif ied) . 

 High temperatures and humidities have provided ideal conditions for the spread and 

 development of this disease and the sudden decline in worm numbers in some fields. 

 The incidence of disease among the worms varies from field to field. In some 

 fields, as high as 50 to 50 percent of the worms were affected. This should help 

 reduce the threat of serious damage to late -maturing soybeans from the next gen- 

 eration of green cloverworms. In addition, many of the larger worms are nearly 

 through feeding, and some have already pupated. 



In most areas, populations are generally somewhat lower than they were a week 

 ago; thus, fewer fields will require treatment. However, the situation still 

 bears watching; the population of worms is still high in some fields. 



Damage from these pests is most likely to occur from the late-blossom through the 

 pod -development stage, when leaf destruction may result in decreased yields. 

 Plants can usually stand losses of 25 percent or more of the leaf surface, even 

 at this critical time. Therefore, do not worry about controlling these worms 

 until about 25 percent of the leaf surface has been consumed and until, by several 

 counts, you find 6 or more worms per foot of row. When the pods approach the 

 filled stage, leaf loss is of much less importance; if late enough, this can be 

 beneficial. 



Reports indicate that 1-1/2 to 2 pounds of toxaphene per acre has not performed 

 consistently well. Carbaryl, by report, has provided good control, but should 

 not be used at more than 1 pound per acre, because high rates will damage beans. 

 Malathion at 1 pound per acre has given good results in the few fields where it 

 has been used. It has a shorter residual life than toxaphene and may not kill 

 newly hatching worms more than a day or two after application. 



Toxaphene may be used with greater bee safety than carbaryl or malathion. If bee 

 yards are present in the vicinity, either use toxaphene or malathion. If you are 

 using malathion, apply in the late afternoon, after bee activity has ceased. 



Potato leafhoppers and plant bugs are also abundant in soybean fields. As you 

 control cloverworms, you control these pests --adding to the benefit to yield. 



