Asian Ladybird Beetle

October 16 and 18, 2000

February 20, 2013: When we were children (and up until about 1999) the predominant “lady bug” in our area (southern Wisconsin) was red in color, with black spots. They were harmless and didn’t bite or smell bad. Once the Asian beetles moved in, they apparently drove the red lady bugs away, for I haven’t seen one in years.

Recently here in southern Wisconsin, we have been plagued with swarms of these beetles. Generally orange in color, usually with spots, they cling to windows and doors and seem to be everywhere. Sometimes they get into buildings, and in a few instances, they have been known to bite people. There has been some confusion as to whether or not these are the common “lady bug.” I tried to learn more about the matter by searching for “lady bug” or “beetles” on the Internet. I was totally blown away by the number of species of them that actually exist. There are many related species, and colors vary tremendously.

Asian Lady Beetle

I sent an e-mail to William Robinson, an entomologist with Orkin Pest Control. He told me that the species in question is Harmonia axyridis, known as the Asian ladybird beetle. The adults often return to the same place each winter, and they live 2 to 3 years, so we may have them again the next several years!

They are also called the Halloween lady beetle (because of their orange color and the time of year when they are often seen) or the Japanese lady beetle (because they were brought from Japan to the southeastern U.S.).

The beetles feed on aphids, so they were sought after by farmers whose crops were plagued by aphids. Because they are hungry, they will bite people occasionally, unlike the smaller native lady beetles. And if they are crushed, they secrete an odorous substance from their legs.

The info I received from Mr. Robinson appears below, reprinted with his permission:

What you have is probably the Asian ladybird beetle (Harmonia axyridis). These insects are household pests nearly throughout the country. They usually make their presence known in the fall and winter when they collect in large numbers around the perimeter of houses and buildings, and a large number of them make their way inside.

These beetles were introduced into the U.S. several times by the USDA to control aphids in some southern states. Adult beetles and the larvae can eat hundreds of aphids each day and are considered a biological control agent.

Asian ladybird beetles overwinter in protected places, and sometimes this includes coming inside the house. These beetles live outdoors during the summer feeding on aphids and perhaps some other pests of ornamental and vegetable plants. They are naturally found in trees, but here in the U.S. they are found in nearly all habitats, from field crops, to vegetable gardens, and ornamental plants. The adult beetles often return to the same sites year after year to spend the winter, and they can live for 2 to 3 years. So a problem this year may mean that you will have a similar problem in years to come (oh, joy!).

The best control strategy for the beetles that have come indoors is to use a vacuum cleaner to remove them from the windows and walls. They are harmless, but if crushed indoors they can leave a stain on carpeting or drapes. A vacuum works well, but you can use an aerosol to knock them down from difficult to reach places, then use the vacuum.

Outdoors in the fall you can try spraying the aggregation of beetles that are on the side of the house with a garden hose and water (to discourage them) or garden insecticide and hose, this sends a stronger message to move on and will kill those you contact with the insecticide. Be certain to use an insecticide that is recommended for treating ornamental plants, in case these are sprayed in the process there will be no harm to the leaves. You may have to spray several times, since more may come and some of those in the aggregation may not have been contacted by the chemical.

Check out these sites for more information on Harmonia axyridis: