What are round-ish, mostly orange and commonly found in October on front porches or near entryways? Obviously the answer is Harmonia axyridis, a.k.a. the multicolored Asian lady beetle or lady bug. This insect, although beneficial to gardens, is no treat when it gathers by the hundreds on your doors or exterior walls in autumn. And more than a few will find their way indoors.
The US government first imported these lovely beasts in 1916 to control pests on pecan trees and other crops, and with great success. The Asian lady bug, darling of countless small children, didn’t turn into an ogre until the mid-1990s. Actually, there is some evidence to suggest the current population is a new strain accidentally released at the Port of New Orleans around 1993. Whatever their origin, they’re in season now along with corn shocks and jack-o’-lanterns.
Lady bugs don’t transmit any diseases, cause harm to structures or suck your blood, and they munch on harmful garden pests. On the flip side, they leave stains, give off a foul odor when disturbed, and will even pinch one’s skin on occasion. It’s their sheer numbers, though, coating a picture window, huddling in a corner of the garage, or swarming an entryway, which unnerve and irritate so many of us.
It turns out that managing lady bugs will reduce your heating costs. These insects want someplace warm and rent-free to spend the winter, and will squeeze through cracks and other openings to get in your house. Caulk around windows, vents and where the cable or other utilities come through the wall. Also seal between the foundation and sill. Ensure that door sweeps and thresholds are tight, and check for cracked seals around garage doors. Install screens on attic vents and inspect all window screens. Those places are where cold air gets in, and by sealing drafts you’ll also exclude lady beetles and other shelter-seeking critters.
If lady beetles are already indoors, don’t swat or crush them because they’ll release a smelly defense fluid which will also leave a yellow stain. For a variety of reasons including the lady bugs’ habit of seeking inaccessible areas, indoor pesticide use is strongly discouraged. Instead, use a broom and dustpan, vacuum cleaner or shop-vac. Try using a knee-high nylon stocking inserted into the hose and secured with a rubber band as a reusable “mini-bag.” Just remember to empty it as soon as the vacuum is turned off.
If you’d like more information, a very good fact sheet courtesy of the folks at NYS Integrated Pest Management is here: https://blogs.cornell.edu/nysipm/tag/multicolored-asian-lady-bird-beetle/
I suppose that homeowners could decorate a giant pumpkin to look like a multicolored Asian lady beetle in hopes that it might scare away the actual lady bugs. So if you see a 100-pound lady bug this Halloween, please don’t swat it.
Paul Hetzler is an ISA-Certified Arborist and a former Cornell Cooperative Extension Educator. His latest book of nature essays, Head of the Class, can be found on amazon
Above photo of Asian lady beetle by Andreas Trepte, CC BY-SA 2.5, via Wikimedia Commons