the mixed blessing of the asian lady beetle

lady beetlesIS THAT A LEAK I HEAR COMING FROM THE UPSTAIRS BATHROOM? Oh, right, no; if it’s October, it’s just the annual shower of Asian lady beetles dropping, one by one, off the screen or the outer window onto the sill–drip, drip, drip (above). On warm late-winter days around February, the sunniest windows inside the house are abuzz with them again, and the sound is more clickety-clack against the panes as they take off and land again, and again.

These non-native “ladybugs,” introduced by the Department of Agriculture to help combat certain agricultural pests, have made themselves right at home in America—and in my house, too. In fall, the south-facing side of the exterior can be teeming with patches of them, as they look for places to tuck into and overwinter.

The USDA imported lady beetles from Japan as early as 1916 as a beneficial insect, to gobble up unwanted pests on forest and orchard trees, but it was probably later releases, in the late 1970s and early 80s in the Southeast, that took hold. Today, multicolored Asian lady beetles have made themselves completely at home around the United States, easily adapting to regions as diverse as Louisiana, Oregon, and mine in New York State.

As much as I like members of the food chain who devour aphids and soft-bodied scale insects and the like, I am not crazy about Asian lady beetles, at least this time of year, who, looking for the equivalent of the cliffside habitats of their native landscape to tuck into and overwinter, go for houses instead.  It would all be fine, if a little sci-fi, except that they stain things and also emit a bad-smelling compound in self defense (such as when you try to scoop them up and toss them back out the door). Sometimes I have hundreds inside at a time (hello, dust-buster).

I can say with first-person authority that they taste really bad, inclined as they are to jump into the bedside water glass or any other food and drink left unattended and then eaten or drunk from without examining it carefully first. Ugh.

I’m not the only one upset. Apparently native ladybugs have been sulking, too—or is that just a coincidence that their populations seem to have dipped drastically in the last 20 years? The Lost Ladybug Project, a program with funding from the National Science Foundation and conducted by Cornell University, is trying to track the status of native species, and asks for “citizen scientists” (meaning us, and even kids) to help observe and photograph whatever lady beetles of any kind they see, particularly each summer.

Get a pdf ID guide to tell the different species apart, and also see the variations within the Asian species.

But how to stop the annoying swarming of these alien invaders? Drugs, perhaps. Recently, there’s evidence that the compounds in catnip oil help. It’s not ready for prime-time yet, but you might want to talk to your family feline about sharing his or her stash of the good stuff.

  1. Amy G. says:

    Catnip oil? Spray bottle? I’ll try it. We have several hundred over for dinner most evenings throughout the late fall and winter here in NC. They’re wonderful for the adjacent rose garden, but seem bored in the colder months. They love the dining room, but they’re disconcerting for our non-gardening guests!

  2. Amy says:

    Margaret, thanks for the info! We too have been invaded this week, and I always feel bad knowing that so many will die before I can get them scooped up and back outside. Other members of my family are not so soft-hearted [or don’t hate aphids so much!] and a bunch of them always end up in the vacuum. Are they just nesting? a mass suicide pact??

  3. Brian G. says:

    They are awful. This year it seems they like to appear from nowhere on my freshly painted white walls and spray their mess as I grab them with a tissue. If they could hold a paint brush I’d put them to work on touch ups as community service!

  4. Cassie says:

    Usually we’d have quite a ladybug party here (the “hidden hills” of western ma) by now, but so far this year they haven’t materialized. Perhaps it’s the two snowfalls we’ve already had? I hiked up Mount Holyoke last week, though, and the Summit House is absolutely coated in them–every side, every surface. I put some pictures on my blog– http://shopclementine.blogspot.com Strangely, I didn’t see them anywhere else on my hike, just on the building.

  5. Newell says:

    They’re swarming here in the Catskills too. I don’t mind them outside, but I don’t want them inside where they might get too comfortable, nest, mate and multiply. I’ve found a Swifter mop otfitted with strips if duct tape the perfect weapon. No mess. No time for them to release any odors.

    1. Margaret says:

      Welcome, Newell. Now you really sound prepared for the onslaught. Impressive! Sort of an update on the old-style fly paper, huh? Hope to see you soon again (and good luck with the incoming).

      Welcome, Amy G. Not sure how it all works, but you can read the data at the link provided…worth trying, huh? Sometimes visitor here look at me (with my last name of Roach) as if I actually like living w/insects. :) I am happy for them to take cover in the siding or whatever to stay alive, but please, not in my glass of water, my supper, or dive-bombing my head.

  6. I had the vacuum out three times this evening for this very invasion. I used painters tape around our outside door on the west side of the house as it seemed to be the source of entry as they squeeze in. That’s all I know to do.

    I wonder if I cut back all of my nepeta and hang the cuttings on the side of the house…


  7. Amy says:

    Goodness, it’s happening here in East Tennessee, too. When we first moved into our house last year, I noted all the dead lady beetle carcasses in the windowsills and thought, “My goodness, but the last owners were slobs.” Now I know, they just couldn’t keep up with the onslaught. I’ve been told that the best defense is a good offense, in making sure the seals around windows and doors are air tight. Meanwhile, I roam with the vacuum hose at the ready, capturing the culprits before they can make a mess. Too bad once they find your house they come back time and again. Kind of like in-laws!

  8. Linda P says:

    I’m happy to hear I’m not the only one that has had an on slaught this year. Five years running my daughter’s south facing bedroom has been home to the native lady bugs. A few here and there that we pop outside the window.
    In recent weeks however the Asian strain invaded, with thousands of them firs trying to unpack in the new unfinished addition. Recently several have made it inside the main house to tuck in for the winter. I find every good experiment has it’s flaws….

  9. My painter had just finished painting a side of the building when they attack, sticking themselves into the wet pristine white paint. What a mess to remove and repaint. I’ve printed your article to share with him.

  10. leslie says:

    My sympathies to all with massive invasions. Our house (in the Hudson Valley about an hour south of Margaret’s) isn’t immune, but there never seem to be more than 40 or 50 at a time, distributed among several upstairs windows on the south and west sides. They get caught in the 50’s-style ceiling lightbulb shields but other than that do no harm. We’ve never had trouble with smells or stains, perhaps because there are so few we have the luxury of being able to leave them alone. In fact I welcome the ones in my office as a terrific way to waste time when I should be working. Using a stiff piece of paper and a cupped hand, I catch them and take them down to the greenhouse, where they do eat up assorted pests – in spite of all the scientific info. that says they don’t at this stage of their lives.

  11. Charity says:

    Oh my, how I wish I’d know this–and you–when I lived in Tennessee! As a first time home owner, I was heartbroken when my new place, complete with fancy spa tub in the master bath, became Lady Bug Central. The windows around the tub were the worst. I really thought maybe I’d missed something in the First Timer’s Handbook.

  12. JJ says:

    While mobs of ladybugs have been crawling all over my parents house, they’ve stayed away from mine. My not-so-scientific theory is that our red house looks like a not-so-inviting giant ladybug…

  13. Margaret says:

    Welcome, Mary Lou. What a mess that must have been. They are said to be more attracted to light-colored houses, which I find hard to believe since mine is as dark as dark olive green can get, and they love it. I think their motto is: “Any port in a storm.” See you soon again.

  14. shelly says:

    And the little stinkers bite! I didn’t believe it until I got chomped on by one of the little devils..but I still do my best to put them outside near the roses so they can snack on tiny aphids instead of big farm girls.

  15. Janet B. Teacher says:

    In our neck of the woods (Bucks County, PA) people say they are attracted to old stone houses, like the similarly innocuous box elder that moves in around Memorial Day. Now I know better. Unlike the box elder, which this spring formed scarlet, undulating clusters on the lilac and agastache that were amazing to watch, the ladybugs offer scant amusement. And they stink, and have stained my linen curtains, which I am loath to take down and wash/iron right now in the event that they soon stain again.

  16. Catherine in Seattle says:

    The ladybug infestations here in Seattle are the result of ladybugs being brought up here from warmer climates, sold in stores, then released in our yards. They are used to hibernating in stumps, etc, but in the urban landscape they are hard pressed for stumps. The best they can do is find a way to get into your house, which is clever, when you think of it. However, they can’t hibernate in your house, it’s too warm. As a King County master gardener I’ve recommended taping over half of the intake vent on a small portable CLEAN vacuum, then gently sucking them up. You can get creative with what you do after that (store them in an unheated garage for the winter? Release in spring?)

  17. dianne dolan says:

    I have then in Maine this time of year. I was told they were not beneficial in the garden like the “good ones”, it’s nice to hear that is not so, and perhaps they r good for something after all.

  18. Barbara Greene says:

    It is reassuring to read all the above comments about ladybugs, since I thought I was about the only one to be so cursed. I kept saying, as I vacuumed, ladybug ladybug fly away home, until I realized that in all likelihood my home was their home. One think I discovered – do not use a small hand-held vacuum, like a DustBuster, because they actually crawl out of them, so I keep the full size vacuum at the ready, right next to the sunny window in my living room. It’s not a fashion statement, but it’s convenient, and the only way I know to keep a bit ahead of their taking over my house. BG

  19. Margaret says:

    Welcome, Catherine. I have read in USDA and university documents variously that the ones in the Northwest rode in inadvertently on trade ships (including to the port of Seattle, and also to New Orleans) or got released by the USDA (at Yakima, for instance, 14,000 were released intentionally around 1980ish). Apparently nobody’s sure.

    As you say in much more recent years they have been for sale as IPM-type agents, to control aphids and such, but that would involve far smaller concentrations being released in any given location, by a home gardener, probably just adding to the populations. It’s all a fascinating puzzle, like so much of the tracing of our impact on nature, isn’t it?

    There are some tips for overwintering the lady beetles in this Ohio State fact sheet, by the way:


    Welcome, Barbara. Yes, the dust buster versus the vacuum…either way, probably good to empty it asap. The fact sheet link about has some suggestions on that, too. And no, you are not alone! I always felt mildly embarrassed about this scourge but now I don’t; it’s just the October ritual, not my housekeeping skills. :)

    Hope to see you both soon again.

  20. Nancy says:

    I’m an extension agent in rural NW PA and we get calls all the time in my office about this annual invasion. Some callers tell me that they’re sweeping up five-gallon buckets of bugs!

    I have to say that my own house is relatively immune – probably because it is more shaded than many of my neighbors and that ladybugs seek out light-colored surfaces in full sun.

    A licensed pest control operator can spray the exteriors of homes, which works too. It all depends on your level of tolerance for pest control and pesticides.

    I recommend to callers that they vacuum up the bugs and get out the silicon caulk gun and apply a bead of clear caulk around their exterior and interior window sills and frames, doors and other ports of entry in a typical home. I remind them that if ladybugs are getting in, they have some air leaks and that cold air is getting in too. Caulk once, foil the bugs and keep the cold winter winds OUT. Biggest problems for bug invasion are log cabins and old homes that have lots of windows and poorly-fitting frames.

    1. Margaret says:

      Welcome, Nancy. All great information, thank you. I bet your calls are busy at this time of year! I re-insulated and re-sided my house and redid all the windows a few years back, so not as many get inside as once did, you are correct. Hope to see you soon again.

  21. Ann says:

    AND they bite! I hate it when they fall from who knows where with no warning and end up behind your glasses or inside your clothes. I hate how box elder bugs smell, too.

    1. Margaret says:

      Welcome, Ann. All of these natural defenses against predation – the scents bug emit when threatened, for instance – are a nuisance, and also so interesting. I love the science behind it, but wish it was not in my water glass on the bedside table. :) See you soon again.

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