Mostly a good guy: multicolored Asian lady beetle

May 5, 2017 2:33 PM
Blog Post

multicolored Asian lady beetle life stagesThe multicolored Asian lady beetle, also known as Harmonia axyridis, is a common insect in the ag landscape and also in urban areas. It’s often confused with plant pests, like Japanese beetle. Generally, it’s a good thing to see them around because the larvae and adults are predatory, and eat soft-bodied insects like aphids.

Forewing color: Ranges from yellow - to orange - to red, with zero to 19 black spots; the wings may be entirely black with red spots. Now you know why the “multicolored” is included with common name. What pattern is mostly consistent is the black “M” on a white plate just above the wings.

multicolored Asian lady beetle wing variation
Note color and spot variation with multicolored Asian lady beetle. Photo by Wikipedia.

Life history: Adults typically live 30 to 90 days, but they can live up to three years. Females lay over 1,600 eggs in a lifetime. Wow! Eggs are laid in small masses and kind look like pale footballs. After hatch, the larvae go through four instars before pupating. Larvae are usually black or grey and have orange-red markings on the abdomen. Plus they usually have cool-looking spikes on their backs. 

multicolored Asian lady beetle life stages
All four life stages of multicolored Asian lady beetle. Photo by Wikipedia.

Population dynamics: Cannibalism plays a role in this beetle species. If they don’t find prey, they will start eating each other or other beetle species. The total number of aphids consumed through the larval stages varied from 90 to 370 aphids, and across all larval stages averaged 23.3 aphids consumed per day. Adult consumption typically ranges from 15 to 65 aphids per day, again depending on aphid species.

Establishment in the U.S.: This beetle is originally from Asia (e.g., China, Japan, Siberia), but was released for biological control of other insects beginning in 1916 in California. During 1978-1981, the beetle was additionally released by state and federal (USDA) agencies in several states along the Atlantic Coast and Gulf of Mexico. Accidental entries have arrived on nursery stock at ports in Delaware and South Carolina. The first extensive populations were not found in the United States until 1988 near the port of New Orleans, Louisiana. Therefore, it is not known for certain whether the lady beetles' establishment in the United States was the result of accidental entries, planned releases, or both.

Iowa status: The multicolored Asian lady beetle was never released by Iowa State University in Iowa. The population we have is the result of the beetles probably flying here from Louisiana, or hitchhiking in a vehicle, although we will never know for sure how they arrived. They were first reported in Iowa in 1994. It is now a permanent, although sometimes unwanted, resident of our state. It is a known predator of soybean aphid, and in that sense, it is a beneficial insect.

Is this beetle a pest? Adults are aposematically colored (meaning their color serves as a warning) and when attacked, will secrete alkaloid-laden "blood" from their leg joints. This behavior is known as reflex bleeding. The "blood" is bitter to the taste and can make your hands reek from handling (speaking from personal experience).However, it has become a serious pest in Iowa vineyards--the alkaloids from a single beetle crushed in a cluster of grapes can ruin large quantities of juice, resulting in off-flavor wine. And if you live in a house in Iowa, you probably appreciate the nuisance factor of these little beetles during October when they defy all our efforts to keep them out and off our walls.

Author: 

Erin Hodgson Associate Professor

Dr. Erin Hodgson started working in the Department of Entomology at Iowa State University in 2009. She is an associate professor with extension and research responsibilities in corn and soybeans. She has a general background in integrated pest management (IPM) for field crops. Dr. Hodgson's curre...