Issue No. 13, Article 3/June 18, 2004
Japanese beetles. Sightings of adult Japanese beetles are no longer limited to southern Illinois. While the numbers of adults caught in traps monitored by Ron Hines, Dixon Springs Agricultural Research Center, continue to slowly climb, other areas of the state are also seeing this insect for the first time this year. Several reports from near the Springfield area as well as a report from Vermilion County have come in this week, all noting the emergence of Japanese beetle adults. Some beetles found were still in the soil but ready to emerge.
Japanese beetles usually begin to emerge in mid- to late June after pupating. During the summer months, females will mate several times during their 30- to 45-day life span. Females lay eggs in mid- to late summer. Larvae hatch and feed on root systems of various host plants in the fall. They overwinter as third instars deep in the soil. As temperatures warm in the spring, the grubs move back toward the soil surface, where they feed on organic matter and corn roots until late spring, when they enter the pupal stage. Japanese beetles have only one generation per year.
As beetles continue to emerge, they will seek host plants to feed on, including corn and soybean. Japanese beetle adults are capable of causing economic damage by clipping silks in corn and defoliating soybean. The Japanese beetle is covered in more detail, including pictures of life stages, in a new fact sheet on the IPM Web site.
European corn borer. Reports on European corn borer have been few and far between. Moth flights have been generally low in most areas, although there are some hot spots of activity. Marc Rigg, at the Pioneer Good Hope Production Plant, has seen a steady increase in numbers of moths caught in his trap since the end of May, with a peak catch of 447 on June 15 (one-night count). Marc also reports second and third instars found in some seed cornfields in his area. Information on the lifecycle, scouting, and management of the European corn borer can be found here.
Soybean aphids. While soybean aphids have not yet been confirmed in Illinois, an extremely low population was confirmed in Wisconsin. Soybean aphids were found in a soybean field south of Kansasville. One or two aphids were found on leaf buds or new leaves after examination of many soybean plants.
Potato leafhoppers. Here's another insect that we haven't heard or seen much about this spring, but don't forget about it! In one alfalfa field (12 inches), an average of about 15 leafhoppers were found per 20 sweeps. Second and third cuttings of alfalfa are generally more susceptible to injury from potato leafhoppers. Signs of injury are usually first seen on field edges or margins as the leafhoppers move into the field. For more information on the potato leafhopper, refer to our insect factsheet.--Kelly Cook