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
If they have been around for a century, why have they just become a nuisance in the last few years? Warming? Have they been a problem in the South historically? I thought they were much more recently introduced.
I’ve lived in Maryland my entire life…and YES they can be a bit of a “nuisance” when they find one particular room in your house a Haven!. I had to share my office every fall/winter with thousands of them. I had them in everything they could wiggle their bodies into. Reading was always fun…having to vacate a few each time I turned a page. I would blow them off with a straw that i kept handy & used as a bookmark. My Kitty tolerated them flying around, landing and crawling on him. His “nickname” was actually Buggy (but I digress). They clustered in the windows, and come spring I had to vacuum up the remaining carcasses. I never noticed staining or smell. I DID notice, that as with ALL bugs, we had few some year and many, many more (like a bumper crop) every so often, as was their natural cycle. They would feast on Box Elder Bugs (another beetle) that would feast on Box Elder Trees. When I moved I kind of missed the little buggers. It took awhile for them to “find me again”. But it also took ME awhile to establish Organic Gardens in my new yard. They come in now every fall and seem to LOVE my spice cabinet for overwintering. I’ve only been “nipped” a few times…which is OK, because as I understand it, they like dead skin cells. Free skincare! So, I’m thinking that as with all things…someone’s “junk” is another’s “treasure”. I can see both sides really-its a matter of Interest (nature an HER cycles), Tolerance (mess & inconvenience) and our ability as Human to be open minded, and have fun with humor as the Arthur has regarding something that “bugs” him (ha-ha). I also think each of our experiences is uniquely our own…and may change (as do our opinions of our experiences) through time, and depending on what else is going on in life. I’m not so sure that I might welcome a “bumper crop” of them this year. But it sure was an interesting experience that I will never forget!