An airborne invasion of ladybugs has turned Sewanee into a pointillist’s drunken joke. Our house has several thousand of them jostling on the southern wall, with a few hundred making their way through hidden cracks to the interior. As I type, they bombard the keyboard. Walking outside, I get them in my hair, down my shirt, into pockets.
A plague of coleoptera? That seems to be the general opinion in town, with calls for chemical weaponry not far behind. More on that later.
Who are these creatures? They are Harlequin ladybird beetles (Harmonia axyridis), also known as Asian ladybugs or multicolored lady beetles. They’re looking for shelter over the winter. Any crack will do. The more the merrier: they call to each other with chemical attractants, possibly because there is safety in numbers.
These insects were first brought from east Asia to America in an attempt to enlist them in our never-ending fight against aphids. So the legions of ladybugs banging against our walls are a testament to the foresight of the USDA and a witness to the prodigious numbers of aphids that, despite their new Asian foes, crowd like feedlot cows on twigs and flower stems.
If swarms of colored beetles were a rare occurrence, the military-industrial-wedding-complex would be charging big bucks for uplifting releases of these merry air-dancers. No such luck: these insects have crossed the cultural threshold that divides purty from plague. How to deal with them? Some companies make lures and traps, decoying the beetles with a mimic of their aggregation pheromones. I have no experience with these devices, but I suspect that they are only partly successful. Like a liquor store on the edge of a college town, you’ll grab some of the swarm, but many others will BYO and head straight to the party. Vacuums work well on smaller swarms and a mesh or nylon stocking placed inside the suction tube (trap it between tube sections) will keep the doomed beetles out of your bag. Or just wait and they’ll disperse or die on their own. Eventually.
But this is not just a story about Homo vacuumus. These beetles may quite literally have a silver lining. Their ecological success is partly due to their invulnerability to disease, a super-power conferred by their “hemolymph” (insect blood). The potency of this vital essence is easily confirmed: poke a beetle and see the defensive yellow ooze of blood emerge from chinks in their legs, staining your hand and releasing a powerful odor. Studies of the antimicrobial properties of the blood show that it contains a chemical, harmonine, that inhibits both TB and malaria. Knowing this, I pick the ladybugs out of my hair with new found respect and even a sense of hope that medical wonders may yet emerge from the entomological onslaught.
The weaponry story does not end here, though. These insects not only carry chemical defenses in their blood, they may also attack competitors with biological weapons. A microbe that lives peacefully on the harlequin ladybug appears to be lethal to native ladybugs. When these natives prey on the eggs of the harlequin ladybug, the microbe attacks and death follows.
In sum: we’re under attack from insects that are in violation of multiple international arms agreements. Enjoy the spectacle.
David George Haskell 
Good to know of their medical potential. When it gets cooler, these guys collect on our upstairs SW bathroom wall. Last winter, on a warmer day , I invited them outdoors by cracking the window. They accepted the invitation.
Good idea: Coexistence.
You should write a book!!!! You have such a great way to tell a story. :).
Thank you! Only a madman would attempt a book.
Funny Stuff.
A telling and colourful illustration of the complex issues raised by biocontrol. Will we ever know enough to say that there will not be unforeseen consequences when we import alien species to control natives — or other aliens? How would we know we knew that? The South Africans have made a good stab at getting it right, though rigorous testing. We can only do our best, is my best guess…but often we don’t even try to do that.
Good point. I think our inability to predict outcomes underscores the immense complexity of interactions in the world.
I hope I’m not dooming us to an infestation by mentioning this, but at our place (near Jump Off) we’ve had very few of these insects. Perhaps they are being eaten by our foraging guinea fowl? However, on the way into town yesterday I got a glimpse of the scope of the invasion as clouds of the beetles smashed their yellow hemolymph onto my car windshield. Good to know that it’s now probably immune to malaria.
Keep your fingers crossed and return to Jump Off with stealth so that they don’t follow you back! Anti-malarial car treatments might be a good line of business…
I read quite a lot about these irritating indoor nuisances last night, David, but no article entertained me with information as yours did. I must say that they are quite bothersome to those of us in village shops. They outnumber the customers and mess with the merchandise without paying for their damage.
The last line of your comment made me laugh Robley. And of course, David, great article. Now I’ve learned more about ladybugs! Chemical ecology is fascinating.
Glad you enjoyed the post Robley. I can imagine that they would be a real pain in the store. Good luck dealing with the onslaught!
Onslaught is putting it mildly. When I opened the door yesterday, there were thousands of dead and dying. The place has a peculiar perfume. When customers leave, I keep trying to spay a little Crabtree & Evelyn, but . . . .
They really like the store! I hope the invasion abates for you soon. Sounds like a real pain.
Just wait until the brown marmorated stinkbugs invade Sewanee:
http://www.nwf.org/Wildlife/Threats-to-Wildlife/Invasive-Species/Stink-Bugs.aspx
Unfortunately, they have even fewer redeeming qualities than the Asian ladybugs, as they are proving to be a serious threat to crops, both commercial and of the backyard variety.
As for the ladybugs, they’ve been a nuisance in our part of Virginia for at least a decade now, maybe longer. If you live in an old house, as we do, there’s really no way to keep them out. We’ve set up a passive sort of control — a Gro-Light lure attached to a plastic bag of doom, like a mechanical Venus flytrap — and we vacuum up the dead ones, but by the end of the winter we’re pretty much reduced to crunching them underfoot and flicking them off our toothbrushes.
You have to keep reminding yourself that it’s not their fault — they think they’ve found a crevice in a nice, warm, south-facing cliff-face somewhere in China — but it’s a grumbling kind of coexistence. And a total ban on ladybug-related tchotchkes in the house.
William
PS — Chickens LOVE stinkbugs. For when the time comes…
The graph in the link you sent is fearsome. Is there no end to the invasive insects? Apparently not.
Your mechanical Venus fly trap sounds ingenious. And the ban on ladybug-themed paraphernalia is probably wise!
We have chickens waiting to serve. (In both meanings of that sentence: in the garden and in the freezer.)
I was going to leave a comment about the marmorated stinkbug in the Mid-Atlantic states, but batesvillian beat me to it. Same story, less attractive insect.
So far, they have not arrived here. I’ve heard that they are nasty.
Dr. Haskell,
I really enjoyed reading this post! It is the perfect combination of creative, informative and interesting. Hope all is well!
Marshall Weber
Thank you, Marshall! Apart from invasions of insects, all is well. I send my best wishes.
For years I lived in an old farmhouse in the middle of fields and we suffered every fall from the ladybird beetle invasion. My husband is very fastidious and their arrival would cause near-panic attacks for him. Someone told us you could vacuum them up, put them in the freezer, then release them in the spring. Once we found a box with a lot of beetles in it sometime during the winter. We set the box outside in near-zero weather thinking that would kill them. But when the weather warmed up they reanimated! As others have said, great to hear about their possible beneficial qualities. Just another argument for why we have to preserve biodiversity. Even the pests have value.
Wow — they are hardy! That box of beetles could be quite a frightening sight for anyone not expecting it…
I went into Foster’s Market in Chapel Hill around 1 pm today to pick up a pizza for our weekly Friday night pizza and video fest. (Lately, we’re addicted to “Borgen,” a Danish series about Denmark’s first (fictional) prime minister and the damage being in charge inflicts on her family life. Fascinating, and what a bizarre language!) There’s a sort of arbor at the entrance and as I passed under it I felt something land on my neck. Before I got to the cashier, whatever it was had gotten a good toe hold on my flesh and I brushed it off vigorously. Or maybe I didn’t, or maybe it was a second attacker, but I suddenly felt another bite, more painful than the first. I reached up and crushed the perpetrator under a finger tip. When I got a look at what it was–crushed and oozing my blood–I was surprised to see a lady bug. I’d noticed another one earlier on my car side window. So I guess we’re being invaded to.
Make that “first (fictional) woman prime minister.”
I’ve read about this — bites — but have yet to experience it. Luckily they don’t (as far as we know) transmit any of those bacteria to us.
Incredibly, I caught one of these in my ear while cruising along on my road bike at about 15 mph yesterday. It was an accident of course and it just barely missed going in my ear canal. Insert your own “bug in your ear” quip here. I also had a few hit me in the face and that stings a bit. They are ubiquitous and plentiful. Something will eventually take advantage of that bounty.
In the meantime, keep mouth closed at speed.
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