What Effects Do Asian Lady Beetles Have on the Ecosystem?

Planned Release

• The Asian lady beetle, known formally as Harmonia axyridis, was first brought to the United States in 1916 with the intention of using the beetles to control insect pests that they feed on. Despite this early introduction, it was not until 1988 that established populations were discovered in Louisiana, which has led to the conclusion that the bugs came uninvited by ship via the port of New Orleans. However, it cannot be stated with certainty whether the beetle became established because of deliberate releases or by hitching rides on ocean-going vessels.

Indoor Swarming

• One of the most noticeable impacts of the Asian lady beetles is their tendency to gather en masse on the sides of homes and buildings after the summer. While native lady beetles spend their time outdoors, the multicolored Asian lady beetle seeks out warmer shelter during winter. In rural communities, these lady beetles can infest homes by the thousands. They can also bite, although this is merely a pinch and is not dangerous. If they are handled or disturbed, they release a yellow liquid from their legs that has a horrible smell. Some people can develop allergies to the bug's body fluids if they are repeatedly exposed to them.

Displacement

• One of the negative ecological effects of the Asian lady beetles is that they displace the native lady beetles as they compete with them for habitat and food. Both the native lady beetles and the Asian species eat garden pests like scales and aphids. It is thought that the Asian lady beetles have become a problem in some ecosystems because the normal checks and balances in their native ecosystems are not in place. This means that their natural predators are not around, and this allows for the population to increase unchecked.

Soybean Aphid Control

• A positive effect of the Asian lady beetle on the agricultural ecosystem in the Midwest is that it is a predator of the exotic soybean aphid. This aphid is also native to Asia and has a destructive impact on the soybean crop, resulting in reduced crop yield and subsequent financial losses to farmers. As the greatest predator of the soybean aphid, Asian lady beetles help reduce their number and are beneficial to the farmer. The Asian lady beetles also feed on the aphids that feed on pecan trees and corn, thereby protecting those crops. While Asian lady beetles are welcomed by some, they are not by those in the wine industry. When the Asian lady beetle inhabits vineyards, they are harvested along with grapes and give wine and grape juice an unpleasant flavor.