Month: July 2025

Winsome Fly Biocontrol Slows Japanese Beetle

A closeup photo showing Winsome fly eggs on three Japanese beetles, including a mating pair with a female Japanese beetle below the male.

Winsome fly eggs are found on three Japanese beetles, including a mating pair (with a female Japanese beetle shown below the male). One or more eggs are laid on each beetle; eggs are nearly always laid just behind the head. The Winsome fly prefers to lay eggs on female Japanese beetles. / Photo Credit: Jacques Lasnier, Quebec, Bugwood.org

By Bill Hutchison, Department of Entomology
University of Minnesota
Hutch002@umn.edu

The Winsome fly (Istocheta aldrichi (Mesnil)), part of the Tachinidae family, is a parasitoid of the invasive pest Japanese beetle (Popillia japonica).

A parasitoid is an insect whose larvae develop in or within a host insect of a different species, eventually killing it.

The Winsome fly was introduced in 1923 in New Jersey as a biological control agent of the Japanese beetle, six years after the Japanese beetle was accidentally introduced in the United States. Since then, the Winsome fly has become established in the Northeastern states and Quebec and Ontario in Canada.

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Woolly Elm Aphid Causes Elm Leaves To Curl

Closeup photo of a group of elm leaves that show varying levels of wrinkling and curling, due to feeding by wooly elm aphids on the underside of the leaves.

A group of elm leaves shows varying levels of wrinkling and curling, due to feeding by wooly elm aphids on the underside of the leaves. / Photo Credit: Linda Williams, Wisconsin DNR

By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665 

Woolly elm aphids (Eriosoma americanum) are a minor pest of American elm. The aphids’ feeding causes leaves to curl at the edges and develop a characteristic wrinkled appearance.

Uncurling the leaves exposes many pale gray aphids on the underside of the leaves, which are protected by the rolled leaf.

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