Beetle can be a pest in homes

Yesterday I was coming home from church and I noticed what appeared to be ladybugs around my door. Upon closer examination, I identified the insect as the multicolored Asian lady beetle (Harmonia axyridis). I thought of my first year in Wisconsin where I was introduced to this sometimes pest.

I was renting an apartment at the time. I thought to myself “How nice, ladybugs.” Little did I realize that these were not the ladybugs that I knew as a child. These insects are considered the super ladybugs from Asia. Within a month, the apartment that I was in was full of these insects. I crushed one and it left an orange stain as well as an awful odor. When I moved out, we ended up fogging the entire apartment and we killed thousands of them. When we vacuumed them up, the odor was so bad, we threw away the vacuum. Sounds worse than the box elder bug I wrote about last week, and it was.

The multicolored Asian lady beetle is a good insect with some bad habits. This exotic insect was introduced from Asia and has spread from Louisiana in the 1980s to most of the Midwest today. As with most lady beetles, this insect is highly beneficial as a predator on insect pests feeding mainly on aphids (especially on aphids that feed on soybeans). These insects create trouble for homeowners in rural areas when they enter buildings in the fall. During warm days in winter and early spring, they fly and crawl in inhabited rooms. Not only are they a pest because they appear everywhere in the houses, but their bite can pinch the skin so as to hurt. Little children often attempt to pick them up, get bitten, and come to you crying. The bites are not poisonous, spread no diseases, and there is no swelling, they just hurt. Some people can be allergic to them, although it is quite rare. Keep in mind that these insects have saved soybean farmers millions of dollars because they eat another exotic insect, the soybean aphid.

These insects are a little larger than “normal” ladybugs being about one-third of an inch in length. They are dome shaped and can range in color from mustard-yellow to bright red-orange to entirely black. The most common color is deep orange. They can have zero to more than 20 spots on their backs. There is a black “M” or “W” (depends if you are looking from the front or back) on their thorax just behind their head.

These beetles fly to light and are attracted to light colored areas. Because of this insect’s instinct, there are traps developed for use against this beetle that can be used indoors. Spraying the outside of the house with a residual permethrin may help with their control. Caulking and sealing will also help keep this ladybug out. Long-term control can be done by planting shade trees on the south and west sides of houses (they want to congregate in a warm sunny spot). Insecticide sprays inside of houses do not work well.

If you should have any questions about these or any other insects, please give me a call at 754-2504 or come by the extension office in the courthouse. I would be glad to help.

(Lance Brower is farm business management and economics extension Stuts-man County office of the NDSU Extension Service. Contact him at 754-2504 or e-mail lance.brower@ndsu. edu.)

Tags: bugs, beetles, home