# Japanese beetle spread in Midwest US

> Live situation record from CLSTR: https://clstr.news/situations/japanese-beetle-spread-in-midwest-us
> Updated: 2026-07-28T23:45:05.000Z. Sources: 4. Developments: 2.

In late July 2026, reports from Iowa and Minnesota detailed extensive damage from Japanese beetles to fruiting trees, ornamental plants, and crops. Experts highlighted the use of the Winsome fly, a parasitic biological control released between 1998 and 2006, as a potential means to curb the beetle populations and reduce reliance on chemical insecticides.

A few days later, Wisconsin officials observed the beetles entering their peak feeding phase across north‑central regions. The same Winsome fly, first introduced in Minnesota, was now being recorded in Marathon County and expected to expand further. Preliminary declines in beetle numbers were noted in southern Wisconsin, with hopes that the fly would similarly lower populations statewide. Homeowners in both areas were advised to employ manual removal, soapy water, and barrier netting as interim measures while the biological control takes effect.

## Timeline

### 2026-07-28: Japanese beetles swarm Wisconsin yards as feeding peaks

Japanese beetles reach peak feeding in north‑central Wisconsin; officials promote the winsome fly biological control and recommend hand‑picking and barrier netting for homeowners.

2 sources. https://clstr.news/cluster/japanese-beetles-swarm-wisconsin-yards-as-feeding-peaks

### 2026-07-25: Japanese beetles threaten crops in Iowa and Minnesota

Japanese beetles damage crops in Iowa and persist in Minnesota, where a parasitic Winsome fly is showing promise as biological control to lessen plant loss and pesticide use.

2 sources. https://clstr.news/cluster/japanese-beetles-threaten-crops-in-iowa-and-minnesota

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Cite as: Japanese beetle spread in Midwest US. CLSTR, https://clstr.news/situations/japanese-beetle-spread-in-midwest-us