History of the
Asian Lady Beetle
in South Dakota

Mike Catangui, Ph.D. - Assoc. Professor / Entomologist

The Asian lady beetle (scientific name: Harmonia axyridis) is a biological control agent imported from Asia by the U.S. Department of Agriculture (USDA) to control aphids and scale insects attacking pecan trees and many other plants.  Like most lady beetles, both the immature and adult stages of the Asian lady beetle feed on aphids and other soft-bodied arthropods and are therefore considered beneficial in agriculture.

Although considered beneficial, Asian lady beetles have an undesirable behavior - they do congregate inside homes and buildings in large numbers during the fall in search of an overwintering site.  Homeowners commonly complain of "lady beetles congregating by the thousands" in ceilings, curtains, window sills, porches, and decks.  In addition,  Asian lady beetles may release a yellow-colored fluid when disturbed that can stain walls and carpets.

According to the USDA, the importation and release of Asian lady beetles started as early as 1916 and continued through the early-1980's.  Thousands of Asian lady beetles were released in Georgia, Louisiana, Mississippi, Maryland, Ohio, Pennsylvania, Maine, Delaware, Connecticut, District of Columbia, and Washington.  In addition, accidental releases via imported nursery items have been documented in Louisiana, Delaware, and South Carolina.  The Asian lady beetle is now considered well established in the United States.

In South Dakota, the Asian lady beetle was first collected in Brookings by Dr. Bob Kieckhefer (Research Entomologist-retired, USDA-ARS-NGIRL) in October of 1996.  A single specimen was collected that year by Dr. Kieckhefer.  Beetles were not collected again until 1999, according to Dr. Louis Hesler (Research Entomologist, USDA-ARS-NGIRL).

Dr. Louis Hesler conducted a survey in 2000 and documented the presence of Asian lady beetles in Brookings, Moody, and Codington counties.  He also indicated that reports of Asian lady beetles congregating inside homes are becoming more common in Brookings County.  

Minnehaha County was the last county to report Asian lady beetles in 2000.  Two households reported "many lady beetles congregating in curtains" to Craig Rosenberg (County Agronomy Educator) in mid-October.  Dr. Louis Hesler has confirmed the identity of these beetles to be Asian lady beetles.

Although Asian lady beetles were never released on purpose in South Dakota, it now appears that they have already found their way into the state.  They are now present in at least twenty SD counties.  The benefit of Asian lady beetles in terms of aphid control, as well as their nuisance factor will be seen in the next few years.