Question of the Week Number 1: December 6, 2018

“Why do I have so many lady bugs inside my house? Do I need to worry about them?”

This is what you’re likely to find inside your walls or attic – hundreds or thousands of the lady bugs.

I’ve had a bunch of inquiries about these seemingly harmless insects over the past several weeks. Just as I had last year at this time. And the year before that.

Let me begin by freely admitting that I’m not an entomologist, and certainly not one who deals with pests of the insides of our homes. However, I’ve done a good bit of reading and listening, so I know enough to get you started.

Close-up photo shows several different colors, all of the same species, Harmonia axyridis.

These are called “Multicolored Asian Lady Beetles” (MALB), and they’re native to eastern Asia. Reports say that they were introduced into the U.S. in the 1970s in the hopes that they would be predators of scale insects and aphids in trees.

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These lady beetles are more aggressive than our native species and are known to bite humans when they become trapped in clothing. They do not break the skin, however, so they do not transmit diseases. However, they do exude a foul-smelling chemical that leaves a heavy aroma in rooms and can cause staining of walls, carpeting and furniture.

Photo from University of Kentucky shows multicolored Asian lady beetles to range from butterscotch brown to bright shiny orange.

Prevention and control…
The lady beetles spend summers outdoors. As temperatures fall in autumn they accumulate on south walls, then invade to warmer conditions inside through cracks in siding, holes in screens and other open spaces. Seal all such spaces to prevent them from entering.
If you already have them inside your house it is usually best not to try to kill the large masses of them. The foul smell they leave behind will become overpowering, plus carpet beetles will feed on the dead lady beetles, then go on to do other types of damage indoors. Instead, seal up openings from your attic into your rooms to prevent their getting into the living spaces.
Use a vacuum to suck up those lady beetles that do make their way into your rooms. Change the bag often to prevent the foul odors from becoming too offensive.

Additional help is readily available…
Google “Multicolored Asian Lady Beetle University” and you’ll get a dozen or more excellent university fact sheets on this insect. Here are links to just a few.

University of Kentucky

Pennsylvania State University

Ohio State University

University of Minnesota

Posted by Neil Sperry
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