No. 12 Article 6/June 10, 2005

Arrival of Japanese Beetles

In a repeat performance of 2004, Ron Hines, senior research specialist at the Dixon Springs Agricultural Center, activated his Japanese beetle traps in late May and has recorded the first captures of Japanese beetles during the first week of June. Over the weekend, Ron had captures of Japanese beetles in traps located in Jefferson, Massac, and Pope counties. Also found in the traps were click beetles (adult wireworms) and June beetles (adult of Phyllophaga white grubs).

Japanese beetles, click beetles, and June beetles caught in a trap on June 7, 2005 (photo courtesy of Ron Hines).

The emergence of the Japanese beetles should serve as a notice for the rest of Illinois. For the next couple of weeks, Japanese beetles will be emerging throughout the rest of the state. Japanese beetles overwinter as third-instar larvae just below the frost line. In the spring, they move closer to the soil surface as temperatures warm. Pupation is completed in late spring, and adult emergence begins in early June. Peak emergence generally occurs 4 to 5 weeks after the initial emergence. At that time, beetles will be readily moving into cornfields and soybean fields to feed on foliage, silks, and pollen. In mid-June, beetles will mate and lay eggs. Larvae hatch and will feed on plant roots and organic matter before descending deeper in the soil in the fall.

It's hard to determine where Japanese beetle infestations will occur this summer. They continue to expand their infestations to areas that were previously unaffected by these insects. As the summer continues, we will provide updates and management recommendations for Japanese beetles.--Kelly Cook

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