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Japanese Beetle News

Current information for homeowners and agricultural producers

Japanese Beetle Life Cycle


Japanese beetles go through a yearlong lifecycle. Adult Japanese beetles tend to emerge in our area around the mid to latter part of June. Those adult beetles, noted for their metallic green head, metallic brown wing covers, and white abdomen-lining "tufts" of hair, mate and burrow a couple inches deep in the soil. There they lay an egg or two and continue the process every few days for a period lasting over a month.

Adults can feed on several hundred plant species, but are especially attracted to smartweed inundated fields and poison ivy or multi-flora rose inundated waste areas. In the crop, the beetles will devour leaves and portions of the tassel while also clipping silks. The white grubs that emerge from deposited eggs are especially sensitive to dry soil conditions, which can increase mortality. Grubs survive by devouring root tissue and possibly organic matter.

Root feeding continues until temperatures drop, usually around October, bringing their activity to a halt. Feeding resumes the following spring. These white grubs, identified by V-shaped" hair arrangements on the underside of the "tail-end," complete development and feeding toward the end of May or early June when they pupate.



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