Ladybugs swarm homes every fall because they need warm shelter to survive the winter. The beetles you see on your walls are Asian lady beetles, not the helpful garden bugs most people picture. They pick your house because your warm siding sends them the signal that it's a safe place to sleep until spring.
I saw my first Asian lady beetle home invasion about six years ago on a warm October day. Hundreds of beetles covered the south side of my house in a layer so thick the wall changed color. They crawled into every gap around my windows and under my siding edges. That first year I had no idea what was happening or how to stop it.
The Asian lady beetle home invasion follows the same pattern every year. Your south-facing walls soak up sun all day and hold that heat into the evening. The beetles sense that warmth and land there first. Once a few settle in, they release a grouping scent that pulls in hundreds more from the area. That's the ladybug fall swarming behavior you see: a chain reaction where warmth draws the first wave and scent draws the rest.
This ladybug fall swarming behavior is driven by daylight and air temps. When fall days drop below about 60°F (15°C) and sunlight hours shrink, the beetles start looking for shelter. Light-colored homes with lots of sun get hit the hardest. Your house acts like a giant heat beacon that the beetles can sense from a long way off.
Having these beetles inside your home isn't just a nuisance. About 10% of people living in heavy beetle areas have allergic reactions to them. These range from itchy eyes and runny noses to asthma flare-ups. Kids can have worse reactions too. When you crush these bugs they release a yellow fluid that makes the allergy worse and stains your walls and fabric.
You need to seal your home before the swarms arrive in September. Check every gap around your windows, doors, and pipes. Put fine mesh screens on your attic vents. Fill cracks in your siding with caulk. I spent one weekend sealing my home's south wall and the number of indoor beetles dropped by more than 70% that same fall.
If beetles do get inside, vacuum them up instead of crushing them. Use a vacuum with a bag so you can throw them out in a sealed trash bag. A gentle touch keeps them from releasing that allergic yellow fluid on your surfaces. For homes with bad repeat swarms year after year, call a pest pro to treat your outer walls before the season starts. Your goal is to make your house less appealing than the next one down the block.
Read the full article: Ladybugs Pest Control: Benefits and Drawbacks
