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Oct. 13, 2020

Ask the Expert: Ladybugs101

Stinkbugs aren’t the only insects crawling their way into homes this Fall. Ladybugs – known as lady beetles – have made their way into homes and while they are harmless, they aren’t necessarily welcomed guests.


Gary Parsons, director of the MSU Bug House and distinguished academic specialist in the Department of Entomology, answers questions about lady beetles and what to do if you notice them in your home.


Why might people be struggling with ladybugs right now?

“The lady bugs, properly called lady beetles, that people are beginning to see around their homes are called Asian lady beetles. All kinds of lady beetles spend the winter as adults in protected places. Most of our native lady beetles hibernate under the bark of dead trees and logs or in leaf litter. However, the introduced Asian lady beetle (scientific name: Harmonia axyridi), normally would hibernate in crevices in rocky cliffs in their native range of Asia. However, rocky cliffs are in short supply here in Michigan, so this lady beetle has adapted to substituting homes and other buildings for protected places to overwinter, sometimes in massive numbers.”


What attracts ladybugs to a home?

“Houses with overlapping siding that the beetles can crawl up under are really attractive to them, especially on the south-facing side, but they can also come in around windows, doors, attic vents and other openings. Once a few arrive and find a suitable spot, they emit an attraction pheromone that brings in many more of these lady beetles. By congregating, they can readily find mates when they emerge again in the spring. Once they find their ways into the wall spaces or attics of homes, they may sense the heat from indoors and find their way into the inner rooms of the house. Under those warmer conditions, that seems to trigger them to seek a way to go back outside and then they frequently are attracted to and will be seen at the inside of windows.”


Can they hurt you or pets? 

“Lady beetles have chemicals in their bodies that make them distasteful if eaten. That is why they are brightly colored in red and black, which is a warning to predators to leave them alone. If pets were to try to eat them, they would probably spit them out rapidly. If they happened to eat a lot of them, it might make them sick, but I am not aware of any records that a pet has ever died from eating them.


“Other than being a nuisance, these beetles are harmless to humans. However, occasionally if one lands on a person’s skin, they will give little defensive bites, which might be alarming, but they don’t cause any damage.”


Are there any natural remedies that may get rid of them? If so, what?

“Since they taste bad, most birds and other larger animals learn to leave lady beetles alone. However, spiders, parasitic wasps, and some predatory insects will eat them, but they don’t have much effect on controlling their populations.”


What other remedies may get rid of them? 

“Lady beetles are important beneficial predators of aphids and other pests in gardens, yards and crops. Entomologists, gardeners and growers often do their best to keep them around and not kill them, since that reduces the need to use pesticides to control those pests. Trying to control them in or around the home should only be done if they become so abundant to be a major nuisance. If beetles find their way indoors, normally vacuuming them up when you see them or capturing them and placing them outdoors is sufficient to deal with them.


“It is generally not a good idea to spray pesticides or use aerosol bug bombs indoors to try to get rid of them. Lady beetles that remain in the attic or outer wall spaces during the winter, will do no damage, and will leave again in the spring.”


At what point do you need to call pest control? 

“Insecticides will kill lady beetles, but again it is not recommended unless they become so abundant to be a major nuisance. For a homeowner or pest control company to have much effect at reducing them, they would have to apply insecticides to them when they are still amassing on outside walls during the Fall. Once the beetles move inside the walls or attic, they are much more difficult to control, and likely would be much more expensive at that point for the homeowner to have a pest control company deal with them.”

By: Caroline Brooks

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