Low numbers of first generation corn borer larvae have infested non Bt corn in Nebraska and most of the High Plains.

Moths were prevalent in the fields over two weeks ago. However, record heat on June 9, followed by several nights and days of much cooler temperatures disrupted their egg laying and egg hatch. More larvae may appear yet in the corn, but very few if any fields have reached treatment levels. The extensive planting of Bt corn has probably helped in keeping the overall corn borer moth numbers down and lowered the potential for treatment level infestations on non Bt refuges.

Corn blotch leaf miners are heavy on the leaves on the lower 1/2 of the plant in the usual areas that have had infestations in past years. They are particularly heavy in areas with open water sources like streams, lakes, and feedlot lagoons. This insect has been increasing in severity over the past few years. Little research has bee done on control. Effective control measures are none to questionable at this point. Multiple sprayings to control the adult fly will result in heavy spider mite numbers later in most years.

Corn rootworm larvae are peaking out as the early larvae are approaching the time to pupate. Seed treatments are not doing so well on many fields according to our crop specialists. Treating the rootworm beetle adults, if they are at a very high number, the previous year, allows the chemical and seed treatments to look much better the following the year.

Very little insect activity is in the soybeans now. Early bean leaf beetle numbers didn’t warrant treatments for the most part. Soybean aphids haven’t appeared yet.