Driving through rural Minnesota this week, the dust clouds rising above the fields were a sure sign: soybean harvest season is in full swing. While that’s welcome news for farmers, it also signals the return of a less-celebrated fall tradition—multicolored Asian lady beetles swarming homes and buildings across the state.
The scientific name for these beetles, often mistaken for native ladybugs, is Harmonia axyridis. Originally introduced to the U.S. from Asia in the 20th century to help control crop pests like aphids, they’ve since become a seasonal nuisance in many parts of the Midwest.
Multicolored Asian lady beetles are especially drawn to soybean fields, where they feast on aphids throughout the growing season. But once the crops are harvested and temperatures begin to drop, the beetles start looking for a warm place to spend the winter. That’s when they migrate en masse toward buildings—particularly those with sunny, south-facing walls.
Unlike native ladybugs, these beetles can bite (though it’s more of a pinch), and they emit a foul-smelling yellow fluid when disturbed. They don’t reproduce indoors, but they do hibernate in large groups, often in attics, wall voids, or behind trim and baseboards. On warm fall or winter days, they may become active again, appearing unexpectedly inside your home.
How to keep them out of your house
Preventing an infestation starts with sealing up your home:
- Inspect and seal cracks around windows, doors, siding, and utility openings.
- Repair or replace damaged screens and weather stripping.
- Consider a perimeter insecticide applied by a licensed professional, especially if you’ve had issues in previous years.
If they get inside
- Avoid squishing them; they’ll stain surfaces and release a strong odor.
- Use a vacuum to remove them quickly and cleanly.
- For best results, insert a knee-high stocking into the vacuum hose and secure it with a rubber band to trap the beetles before they reach the vacuum bag or canister.
- Dispose of the beetles outdoors and clean the vacuum to prevent lingering odors.
While the annual beetle invasion can be frustrating, it’s a temporary issue. With a few preventative steps and a good vacuum on hand, you can keep your home beetle-free and enjoy the rest of the fall season in peace.
Find more information about multicolored Asian lady beetles.