Japanese Beetles and Monarch Butterflies

Invasive Japanese beetles have been wreaking havoc on farms and in gardens across the East Coast and Midwestern United States for decades. Beetle larvae and adult beetles eat the roots, leaves, and flowers of many important agricultural and ornamental plants and trees.

New research shows that this invasive species may also be a significant threat to the habitat and survival of one of America’s favorite insects: the monarch butterfly.

A monarch butterfly feeding on swamp milkweed, a common species of milkweed in the midwestern and northeastern United States.

Monarch butterflies depend on the native plant milkweed for habitat and food throughout their migration routes, from Mexico to Canada. Japanese beetles have been found feeding on milkweed flowers, decreasing their fruit and seed sets, and disrupting the next generation of plants. Monarch butterfly populations have already decreased dramatically--around 90%-- in the past 20 years, primarily due to habitat loss, including milkweed decline.

In 2016, the Oregon Department of Agriculture detected Japanese beetles in and around Washington County. ODA recognizes Japanese beetles as a threat to Oregon’s economy and natural ecosystems, and is starting its third year of its eradication and prevention project.

Read more about the study from the University of Kentucky.

[TAGS: Invasive Species, Japanese Beetle threat]