Are Multicolored Asian Beetles Bugging You?

This article was originally published on October 26, 2009 and expired on November 5, 2009. It is provided here for archival purposes and may contain dated information.

The multicolored Asian lady beetle, Harmonia axyridis first entered this country through releases made as far back as 1910. More recently, the USDA made releases in the late 1970s in an attempt to help suppress aphids that were plaguing pecan farmers. Other accounts have the beetle entering the country through different means. Regardless of the entry method, multicolored Asian lady beetles, aka Japanese lady beetle or the Halloween beetle, have become established throughout much of the country. They eat many species of aphids and scale insects, including the soybean aphid, which can save farmers money by reducing the need for aphid control.

However, they are also considered a pest species, especially by grape and other tender fruit growers. One beetle mixed into the grape juice used for a bottle of wine will ruin the flavor.

Additionally, the adult beetles look for places to overwinter each fall. In their ancestral home back in Asia, beetles would seek caves (typically in limestone cliffs) in which to overwinter. Caves are in shorter supply in southern Illinois so they seek the next best thing, our homes. Once inside, they settle into corners and crevasses. On warm days, they can "wake up" and fly around the house, becoming a nuisance. Pick one up and the smell it exudes is quite noxious. This is due to a phenomenon called reflex bleeding. They can bleed from their joints at will. The hemolymph (blood) they exude is a toxic-smelling concoction that helps protect them from being eaten.

Home owners can control entry into the house by having tight-fitting screens, caulking cracks and painting the house a non-white color. Vacuum up the beetles that do enter the house in spite of exclusionary tactics. Pesticide applications are not recommended since you would still have to vacuum their dead bodies up. That would be no more difficult than vacuuming their live bodies up. Additionally for most the fall, the beetles will be congregating around windows and doors to your house on warmer sunny days.

Source: Douglas Jones, Extension Specialist, Integrated Pest Management, jonesd@illinois.edu