Why do ladybugs cover your windows and walls in a creepy crawly blanket? Since when do ladybugs swarm? Well, since the Asian lady beetle (Harmonia axyridis), a native of eastern Asia, became naturalized in the United States—a process that began with an accidental introduction in Louisiana about 20 years ago.
This beetle looks a lot like the native ladybug: yellow to red coloring, typically with black spots, but sometimes with none. In the fall, Asian lady beetles are attracted to sunny, south-facing walls. They seek out cracks and other openings, where they hibernate for the winter. When the weather gets warmer, they start moving around, and some wind up on the inside of your windows rather than the outside.
The Asian lady beetle is good in some ways because it eats aphids and other plant pests. But its nuisance value is high: in addition to the icky swarming habit, the beetle has a tendency to leave stains on carpets and walls.
Get rid of Asian lady beetles by vacuuming, and pest-proof your home by caulking cracks and openings. Plant trees to shade the sunny side of your house, which will make it less attractive to the beetles.
Photo by Tracy Walsh