Ubiquitous lady beetles annoying, but otherwise harmless
Lady beetles, other pests seeking winter shelter
What are these bugs on my house, in my garden?
Good guys a nuisance in large numbers
The little yellow, orange and red insects collecting at your door and on the side of your house are lady beetles, commonly referred to as ladybugs. As the beetles prepare to overwinter, they seek out shelter and release a chemical that attracts more beetles when they find a good location.
Lady beetles are good insects, and if they have picked your home or garden to wait out the winter; do not be concerned. The beetles typically look for shelter in October as temperatures begin to drop and will be a nuisance for a few weeks. When temperatures drop below freezing, the beetles will disappear.
Multicolored Asian lady beetles were introduced into the United States by the U.S. Department of Agriculture to help control soft-bodied insects such as aphids and pine scales. Most lady beetles feed on aphids, scales and other insects that cause plant damage. This species has been introduced at least six times since 1905 but has been common in Kansas for just four or five years.
More than 200 species of lady beetles live in North America, but the only one that is commonly attracted to buildings is the multicolored Asian lady beetle. This species is similar to the more familiar convergent lady beetle and cevenspotted lady beetle, but it is distinguished by the variation in color and markings. The backs of the multicolored Asian lady beetles tend to have either nine spots on each side or no spots at all.
Almost all species of lady beetles seek out sheltered locations to overwinter as adults. Convergent lady beetles migrate to higher elevations where they, like other species, creep into cracks and crevices, under bark and into fallen leaves to wait out the cold. Convergent lady beetles are often collected to be sold for insect control. They can be gathered easily when they congregate in the fall. Homeowners and plant producers purchase the lady beetles to control aphids in gardens and greenhouses.
As I camped last week in a colder climate, I found thousands of multicolored Asian lady beetles in the restroom at the camp site. They apparently crept into the facility to wait out the winter but had frozen to death without more protection.
Vacuum or sweep multicolored Asian lady beetles that make their way inside. They will not damage the structure of your home, but they can be quite a nuisance as they fly around. Occasionally they will pinch bare skin. The beetles also will emit yellowish-orange blood as a defense. This liquid has a foul odor and leaves behind a stain. Remove the vacuum cleaner bag after vacuuming and release the beetles outside or throw the bag away. Lady beetles will crawl out of bags left in the house after use.
Sealing any cracks or openings on the exterior of your house will help keep the lady beetles from entering your home, but finding every hole is difficult. In extreme cases, an insecticide can be used around the outside perimeter of the structure. Wettable powders and pyrethroids will be the most effective. Always read the label before applying any product.
Filling holes and cracks will protect your home from other pests, too. Mice only need about a quarter-inch hole to squeeze through, and they are looking for a warm place to spend the winter along with spiders and lots of other bugs. Sticky traps can be effective at monitoring and controlling populations of insect pests. Cleaning your house regularly to destroy nests and webs also will help eliminate spiders and insect pests inside the home.
Remember, the little guys are just trying to keep warm, too.