Are ladybugs invading your home? Those are probably Asian lady beetles -- and they’re harmless.
As the weather starts to cool off, these beetles start looking for places to hide away throughout the winter. Native species, like the ladybug, find a home beneath tree bark while the introduced Asian lady beetle prefers to crawl up under the siding of your home. They won’t hurt you or your home though.
They feed on aphids, which is good, because aphids are bad. Aphids feed on trees and shrubs and can spread diseases between plants. They suck plant sap from leaves and steps, causing distorted growth, yellowing of foliage and premature leaf drop.
What’s a multicolored Asian lady beetle?
Ladybugs are bright red with black spots. Multicolored Asian lady beetles have a black M-shaped pattern directly behind their heads.
Adult multicolored Asian lady beetles are large, about 1/4 inch long and 3/16 inch wide. Their coloration varies from bright orange to dull yellow and they have up to 19 black spots or no visible spots at all.
The multicolored Asian lady beetle is not a protected species.
What is their lifecycle like?
Female multicolored Asian lady beetles lay yellow, oval-shaped eggs in clusters on the underside of leaves where aphids are present. The eggs hatch into larvae with long legs and are black with red-orange markings.
The larvae consume many aphids and scale crawlers. They eventually turn into pupae that attach to plant leaves. Adults emerge to begin feeding, mating, and laying eggs. Several generations are born each summer. Adults can be found on a wide variety of trees including apple, maple, oak, pine, and poplar.
Lady beetles can live up to three years as adults.
How did they get to Michigan?
The multicolored Asian lady beetle is native to Asia.
They were introduced to southeastern and southwestern portions of the United States to help control aphids on pecan trees back in the late 70s. According to MSU, some believe those deliberate attempts failed and the beetle became established after “jumping ship” somewhere along the Gulf Coast.
It spread rapidly throughout the U.S. and southern Canada. It was first found in Ontario in 1992. MSU said one reason for their large numbers is the soybean aphid, which was discovered in Michigan and other midwest states during the summer of 2000.
Thousands of those aphids can be found on a single soybean plant and the lady beetle takes advantage of that food source.
Can lady beetles hurt you?
Not really, but they can be annoying.
Lady beetles have chemicals in their bodies that make them taste bad if you eat them (don’t eat them, not even for the crunch).
Their colors are actually a warning to predators telling them to leave them alone. If you have a pet that doesn’t mind the taste of ladybugs and they eat a lot of them, it might make them sick.
“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,” Gary Parsons, director of the MSU Bug House, said.
Why are they in my house?
While most native lady beetles hibernate under the bark of dead trees and logs or in leaf litter, the Asian lady beetle looks for somewhere else to hide. That’s because they normally would hibernate in crevices in rocky cliffs in their native area. Since Michigan doesn’t have many areas like that, they find their way into homes and other buildings for protection over the winter -- sometimes in very large numbers.
The Asian lady beetle prefers houses with overlapping siding that they can crawl up under, especially on the south-facing side of the home. They also enter through windows, doors, attic vents and other openings. They are attracted to lights and light-colored buildings.
Unfortunately, once a few find their way into your home, they emit an attraction pheromone that will call more lady beetles to move in. That’s so they can easily find mates when they emerge in the spring. They do not breed or reproduce in your home.
“Once they find their way 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,” Parsons said.
Do they have any natural predators?
Because they taste so bad, most birds and other large animals learn to leave lady beetles alone.
There are some spiders, parasitic wasps and other predatory insects that will eat them. According to Parsons, that doesn’t have much effect on controlling the population of lady beetles.
If I don’t want to start breeding spiders in my attic how else should I get rid of them?
First of all, nobody told you to start breeding spiders in your attic (definitely don’t start breeding parasitic wasps).
So, what can you do to get rid of lady beetles? Parsons emphasized the importance of lady beetles because they eat aphids and other pests in gardens, yards and on crops.
Many Entomologists, gardeners and growers do their best to keep lady beetles around and not kill them since they reduce the need to use pesticides to control pests.
Parsons said you should really only try to control them in and around your home if their numbers grow so large they become 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,” Parsons said.
Parsons said you shouldn’t spray pesticides or use aerosol bug bombs indoors to try to get rid of them. Lady beetles that stay in your attic or outer wall spaces during the winter won’t do any damage and will leave again in the spring.
“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,” Parsons said.
How should I get them out of my house?
You can try to prevent them from entering your home in the first place by caulking or sealing cracks and crevices, but that can be difficult in some homes. If anything, you can caulk around outlet and switch boxes, ceiling fixtures, heat ducts and other openings to keep the beetles in the walls.
Michigan State University Extension recommends the safest and easiest way to get them out of your home is to suck them up in a vacuum and change the bag or take the shop-vac outside and remove the beetles.
If you start seeing stink bugs this fall though, you are encouraged to kill them by drowning them in soapy water.
Read: Let’s talk about Michigan stink bugs: Why are they here? What should you do about it?
Sources: MSU Ladybugs101, Ladybugs are driving me crazy, from fields to homes, Aphids