Why Ladybugs Swarm on Your House

All of a sudden, on a warm, sunny day, swarms of ladybugs converge right on the sunny exterior of your house, garage or shed. Don't you hate it when that happens?

Why They Do It

Ladybugs swarm because they're looking for a warm place to hibernate for winter.

They hibernate in clusters. When one of them finds a suitable place, it releases a pheromone that attracts a couple gazillion more of them. In fact, the pheromone can keep the ladybugs coming back year after year.

Not content to just sit there soakin' up the rays and workin' on their tans, they enter the house in droves. The kids don't have to stand there holding the door open, either.

Ladybugs simply find loose-fitting screens, cracks, and vents, and soon enough, they're house guests. It’s a phenomenon that causes a great deal of exasperation. And they don't even have a name for it!

When and Where It Happens

This phenomenon happens every fall in the eastern U.S. and Canada. In southern New England where I’m from, it occurs on warm, sunny days in October and even into early November.

Ladybugs appear to be most attracted to houses with natural wood siding, houses in wooded areas, light-colored houses warmed in sunlight, and older houses with lots of crevices.

While they are pests, they're not harmful to humans or pets, and they don't reproduce during hibernation or damage structures.

Prevention Is the Best Solution

  • To keep the bugs from getting in, repair loose-fitting windows and doors, seal cracks, and secure vents.
  • If they get in, suck them up with a vacuum cleaner and release them outside, otherwise the survivors can crawl out of the bag and re-infest your house.
  • Their bodily fluids are smelly and can stain, so avoid squishing or sweeping them.
  • If you want to use an insecticide on them, select one that has pyrethrin as the active ingredient. Pyrethrin is a derivative of the chrysanthemum plant and is safer than permethrin, which is highly toxic to cats.

Asian Lady Beetles
Asian Lady Beetles

Fun Facts About Ladybugs, Lady Beetles, and Asian Lady Beetles

  • Ladybugs are a kind of beetle.
  • Superstition has long held that they are a symbol of good luck and that killing one is bad luck. My hunch is that this superstition has resulted in far more ladybug lives being saved than episodes of good fortune.
  • There are some 400 species of ladybugs in the U.S., and most of them are beneficial.
  • Worldwide, there are over 40,000 different species of beetles.
  • Ladybugs are voracious predators, consuming aphids and other insects that are harmful to plants. That's the silver lining in this cloud of ladybugs. If you have houseplants, it may behoove you to become a ladybug rancher.

Where Asian Lady Beetles Come From

There's another species of beetle that will probably swarm your property and that you're likely to confuse with the ladybug. That would be the multicolored Asian lady beetle. It, too, is beneficial.

It exists in the US because the USDA released the Asian lady beetle in Georgia and other southern states between 1978 and 1982 as a natural control for pest insects. But that bunch vanished and no others were seen until 1988, when they showed up in Louisiana, apparent stowaways on a ship docked in New Orleans. Now, they're all over the eastern U.S. and Canada.

Here's how to tell it apart from the domestic ladybug:

  • Its color ranges from yellow to yellowish-orange and it has a bunch of black spots on the dome-like shell that covers most of its body.
  • Some highly trained and compensated research scientists have determined that 19 is the maximum number of spots you'll find on the Asian lady beetle.
  • The pronotum, that collar-like area between the head and wings, features a marking that resembles a black capital M (or a capital W, depending upon from which angle you view the little darling).

If you're really, really bored on a day when swarming occurs, try gathering a jar full of Asian lady beetles and counting their spots. If you find one with more than nineteen spots, some scientist somewhere will probably give you some sort of prize.

A Parting Song to Sing for Ladybug Fever

You know how songs can get stuck in your head (some call them earworms)? It always seems to be an annoying song, too, doesn't it. Well, let me share my present earworm with you.

It's that 1959 Billboard #14 hit, "Lucky Ladybug," by Billie and Lillie. And all I can remember are the opening words: Lu-cky La-dy bu-ug, luckyladybug, da-da, da, da, da-da. Jeez, I hate it when that happens.

Comments 19 comments

Diana Lee profile image

Diana Lee 4 years ago from Potter County, Pa.

We were never bothered much by these invaders until the late 1990s, rumor had it then they had been released here in Pennsylvania to kill gypsy moths or other types of insects harming our trees. Asian beetles will bite you. That in itself is annoying and our trees are still victims of gypsy moths and ash bores. I have found a better way to remove them from window sills in our homes. Duct tape is sticky enough to pluck them right off the surface. They will not lite on a fly sticker and like you said swatting them will leave a nasty residue. I don't like spraying toxic chemicals inside which likely has little effect on them and a vacuum will not kill them it only gives you a way to carry them outside. This is a good topic. Voted up.

Bob Bamberg profile image

Bob Bamberg 4 years ago from Southeastern Massachusetts Author

Hi Diana, nice to have you stop by. God Bless duct tape! Now there are 1002 uses for it. It apparently took a number of years for them to reach your area.

I first became aware of the swarming around '93 or '94. When I was a kid back in the 50's we had ladybugs but I don't remember them swarming in the fall.

I have a niece who lives just northwest of Boston and she called me in a panic one day in the mid 90's. She had come home from work and her kitchen ceiling was plastered with ladybugs. Fortunately, we've only had a few get in the house over the years.

Another cluster hybernator is the boxelder bug and I'll be doing a hub on that soon. I don't have a problem with them, but I know some folks who have.

Thanks for the great comments and the vote. Regards, Bob

Lois 2 years ago

How do you stop them?

Jen 2 years ago

I just leave them be... they do no harm.

Bob Bamberg profile image

Bob Bamberg 2 years ago from Southeastern Massachusetts Author

Hi Lois, the only way to stop them from getting inside your house is to make sure there are no holes in screens, gaps around windows, etc. That's almost impossible to do because most of us aren't aware of those little flaws. You'd just have to do an inspection to find possible entry points. Thanks for stopping by.

You're right, Jen, and if you have houseplants, they'll even eat the aphids, spider mites, and other pests that terrorize them. Nice to have you stop by.

Toni 2 years ago

Is there a difference between the red lady bugs, and the orange Asian lady beetles? We have the orange ones, and I was told by my local garden store clerk that they had no redeeming benefits.

Bob Bamberg profile image

Bob Bamberg 2 years ago from Southeastern Massachusetts Author

There's a difference, biologically, Toni, but to the average person they're no different. I would disagree with the garden store clerk and, in fact, am surprised that he or she said they had no redeeming benefits.

They'll eat aphids, scale, and other soft bodied insects that feed on and damage plants in gardens, ornamental landscaping and crop farms. Glad you stopped by.

Bob Bamberg profile image

Bob Bamberg 2 years ago from Southeastern Massachusetts Author

Hi Nyoma, thanks for stopping by. You're probably getting the box elder bug, which also congregates in large numbers, finds cracks and openings from which to get into your house, and are a real nuisance.

They don't bite or sting, they don't carry diseases, and don't cause major damage to trees, although they can cause deformities in some fruits and the yellowing of leaves. During the spring and summer, they feed on box elder, maple, ash and some fruit trees, .

If they get in your house, their droppings can stain fabrics and some painted surfaces, and if you squash them, they release a pretty awful odor. Like with the lady bugs, it's best to suck them up with a vacuum.

mary615 profile image

mary615 24 months ago from Florida

I had a serious problem with aphids on my Hibiscus plants. Someone told me to get some Ladybugs and where to order them online. I ordered some and turned them loose on the plants. Within two hours all the aphids were gone, and the Ladybugs flew away!!

Great info here, voted UP, etc. and shared.

Jackie Lynnley profile image

Jackie Lynnley 24 months ago from The Beautiful South

I have found lady bugs inside but I just toss them out; would never kill one. They were a favored toy friend in my childhood! I was told way back then they brought luck; so I guess they do!

Bob Bamberg profile image

Bob Bamberg 24 months ago from Southeastern Massachusetts Author

Hi Mary...Lady bugs are voracious predators of aphids, spider mites and other plant pests. Too bad you had to buy them...anyone up here could have mailed you all you wanted! Nice seeing you, thanks for the votes.

Most people I know try not to kill them, either, Jackie. I think the reason is 3-fold: they're harmless unless you're an aphid or other tiny plant pest, their bodily fluids stain if you swat them, and by superstition they're good luck charms. Thanks for stopping by.

Fran Fry 12 months ago

I just had a swarm of Lady bugs, but the swarmed me when I went outside and they kept biting me. I know that sounds weird, but this is the first time I've had this happen. Usually they don't bite, and I didn't think they ever would.

Bob Bamberg profile image

Bob Bamberg 12 months ago from Southeastern Massachusetts Author

That sure is a strange experience, Fran, and I don't know why they'd swarm you. Stranger things have happened, I suppose. I wonder if anyone else out there has had a similar experience? Thanks for stopping by and commenting.

Clowes 11 months ago

I just walked outside with my husband and we were greeted by swarming ladybugs (of some sort) and we had been outside 2 hours prior and they were not there. They were just everywhere and we have never had the problem here before and even when we walked out to our driveway they were floating everywhere and they kept landing on reminded me of the movie "The Birds" only with ladybugs. Ugh!!! We didn't give them a chance to stay on us long enough to bite but my husband has mentioned they bite before because we have had about a dozen in our upstairs before. But absolutely nothing like this!! I don't know anyone who has had this issue here in makes me not want to leave my house but also makes me feel trapped. We have lived in our home for a little over a year and we never had this problem a year ago...sorry but I am all for killing off pests...and in this situation these ladybugs are idea how though at this point, just hoping few get in as I have 4 children.

Bob Bamberg profile image

Bob Bamberg 11 months ago from Southeastern Massachusetts Author

Hi Clowes, nice to meet you. It appears that last year you dodged a bullet but this year you got two in the hat. Any lady bugs that got in will probably show up on ceilings or high on walls to start with. If you swat them, they'll stain the surface. You might consider it a silver lining that they'll hibernate, so won't breed. If you have houseplants, they might be helpful when they wake up in the spring because they eat aphids, spider mites and other small pests that can damage houseplants. Best wishes as you face another Nebraska winter (and we think we have it tough here in New England...ha). Thanks for stopping by and commenting.

Kitty Curry 11 months ago

Got a million of them outside now freaked my 16 yr old son out lol but I told him it was a sign of good luck never seen this many at one time before

Bob Bamberg profile image

Bob Bamberg 11 months ago from Southeastern Massachusetts Author

Hi Kitty, nice to meet you. Your son should be glad they weren't mosquitoes! All I've ever seen were dozens of them on my house, but I've talked with people who said they had hundreds. Luckily not many of them actually make it indoors. Thanks for stopping by and commenting.

Paige 6 days ago

OMG I was just taking the dog out and became covered one even in my mouth yech Had to shake them out of my clothes and hair the dog had to be brushed out. I live in a tan house in a wooded area when will it end!!!!

Bob Bamberg profile image

Bob Bamberg 6 days ago from Southeastern Massachusetts Author

Hi Paige,

I live in a tan house, too and we've got some unseasonably warm weather coming the next few days...mid 80' I expect to see the swarms, too. It should only last a few days. Thanks for stopping by and commenting.

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