Ladybugs in Your House in Scarborough: Why They Come In and How to Stop Them

If ladybugs are crawling on your windows and ceilings in October, they are almost certainly multicoloured Asian lady beetles looking for a dry place to spend the winter. They do not sting, spread disease or eat your food, and they do not breed inside. Vacuum the ones indoors, then seal the gaps on the sunny side of the house before next fall. Health Canada says no pesticide is registered for ladybugs in Canada, so sealing is the real fix. If you want the gaps found for you, our pest control in Scarborough starts with a free inspection.

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Which ladybug is in your house?

Not the ladybug from the picture books. The one gathering in Scarborough homes every fall is the multicoloured Asian lady beetle (Harmonia axyridis). Health Canada's ladybug page says it was brought to North America in the 1970s to control aphids and other crop pests, and it has since become one of the most common lady beetles in the country.

How to tell it apart:

• Size and colour. 6 to 10 mm long, anywhere from mustard yellow to dark reddish orange, according to Health Canada. Two beetles from the same window sill can look like different species.
• Spots. Anywhere from none to many. Penn State Extension's fact sheet counts up to 18 black spots on the red forms, and notes that some beetles are black with a few orange or red spots instead.
• The marking behind the head. The giveaway is the white area just behind the head with a black mark shaped like an M (or a W, depending on which way you look at it). It is the quickest way to tell this species from the smaller native ladybugs.

The native species you see on garden plants in summer rarely come indoors in numbers. If you have dozens or hundreds on the inside of a window frame, you have the Asian species.

A cluster of ladybugs on your wall in October is not an infestation in the usual sense. Nothing is breeding, eating or damaging the house. It is a shelter problem, and shelter problems are fixed with a caulking gun, not a sprayer.

Why they pick your house

Asian lady beetles spend summer outdoors eating aphids. When the nights turn cold they look for a protected, dry place to overwinter, and a house wall in full afternoon sun, with gaps behind the trim, is the best shelter a Scarborough street has to offer.

What the extension research says decides which homes get them:

• Sun on the south and west walls. Health Canada and Penn State both point to sunny, southwest exposures. Penn State describes the classic pattern: a sunny, warm afternoon after a cold night, with the beetles landing on walls that catch the afternoon light. Beetles land there first, then hunt for a crack to crawl into.
• Contrast, more than colour. The University of Kentucky's structural infestation fact sheet found contrasting features attract them more than the siding material or the house colour does. Dark shutters on a pale wall, white window trim on dark brick: those edges are what a flying beetle homes in on.
• Fields and trees nearby. Health Canada says homes near fields or forested areas are more prone to them, and Kentucky says the same about homes next to woods.
• Shade protects. Kentucky notes that houses shaded from the afternoon sun are less likely to draw a swarm.

What that means on a Scarborough street

Scarborough has more of the conditions above than most of the city. Parks Canada describes Rouge National Urban Park, on the east edge of Scarborough, as a mix of forests, meadows, wetlands and agricultural fields, exactly the kind of land Health Canada flags. Homes in Malvern, Morningside Heights and the Port Union end of West Hill sit close to it. The Highland Creek valley runs through Morningside and Highland Creek, and the treed ravines along the Bluffs back onto Guildwood, Scarborough Village and Cliffside.

The housing adds the contrast and the gaps. A lot of Scarborough is postwar brick bungalows and back-splits, many with painted trim, aluminum soffits and storm windows that have shifted over sixty years. A south-facing bungalow with white trim on red brick, facing a ravine, is about as attractive to an Asian lady beetle as a building gets. A newer townhouse on an internal street with a shaded back wall is far less so.

When they show up, and when they come back

Penn State puts the start of the overwintering flight around the beginning of October. Kentucky records swarms from September to November with most in October, flights peaking on sunny afternoons when the temperature climbs back to the mid-60s Fahrenheit (about 18 C) after cool weather. Search interest tracks the same calendar: in the Google Keyword Planner figures we pull for the Toronto area, "ladybug infestation" jumps several times over in October and drops away by December.

There is a second wave most people do not expect. Health Canada notes that most beetles that get inside die within a short time, but some hibernate in attics and wall voids, come out during mild weather, and make a bigger appearance in late winter or early spring when they leave to mate outdoors. Kentucky adds that the beetles you see in March are the same ones that went in last fall, not a new generation. So a January thaw that brings ladybugs to an upstairs window does not mean they are multiplying. It means they were in the walls all along.

For the other insects doing the same thing in the same weeks, cluster flies, boxelder bugs and stink bugs, see our fall pests in Scarborough guide. For what keeps moving through January and February, see winter pests in Scarborough.

Are Asian lady beetles harmful?

To the house, no. Kentucky says they do not attack wood, food or clothing, and Health Canada says they do not sting, transmit disease or infest food supplies. They are a nuisance with three real downsides:

• They pinch. Penn State and Kentucky both report occasional bites. Kentucky compares it to a pinprick. It is seldom more than that.
• They stain and smell. When disturbed, they release a yellow fluid from their leg joints that smells bad and can mark walls, curtains and countertops. Crushing them or sweeping them with a broom makes it worse.
• Allergies in some people. Penn State links heavy indoor infestations to eye and nose symptoms and asthma in sensitive people, and notes that some people who react to cockroaches also react to lady beetles. If someone in the house wheezes or itches when the beetles are around, talk to a doctor. We are pest people, not health advisers.

Penn State also warns that a dog or cat that eats a lot of them can get irritation inside the mouth from the same defensive chemical. If a pet seems to be snacking on them, keep the beetles off the floor and call your vet with any concerns.

How to get ladybugs out of your house

Once they are inside, Health Canada's advice is short: sweep or vacuum them up, then seal and discard the bag so they cannot escape. A few details make that work better.

1. Vacuum, do not swat. A broom or a tissue crushes them and releases the stain. Use the hose attachment.
2. Put a stocking in the hose. Penn State's trick for bagless vacuums: push a nylon stocking into the hose, hold it in place with a rubber band, and the beetles collect in the stocking instead of the canister. Tie it off and put it in the garbage. With a bagged vacuum, take the bag out after each session and seal it.
3. Find the entry point inside. Watch where they appear each morning. A gap behind a baseboard, around window trim, at a ceiling light or around the exhaust fan is often the inside end of the path. Penn State suggests sealing those openings, with tape as a stopgap until you can caulk.
4. Turn off the attraction where you can. Beetles indoors move toward light. Keeping the blinds down on the worst window on a sunny afternoon cuts the number crawling out onto the glass.
5. Be patient. Kentucky notes there is no quick fix. You will keep vacuuming a few here and there until spring.

That carpet beetle warning is worth taking seriously in an older house. If you have had a big lady beetle year and later find small, hairy larvae or irregular holes in a wool rug, see our carpet beetle control in Scarborough page.

How to keep them out next year

Health Canada calls preventing entry "the only way to control them," and every extension source agrees. Kentucky notes that gaps of 1/8 inch or less are enough to let them in, so this is fine work. The best time to do it is late spring or summer, before the October flight.

Start on the south and west walls and work through this list:

• Windows and doors. Caulk around frames and jambs. Replace torn screens. Fit a tight door sweep and weatherstripping on sliding doors.
• Siding, soffits and fascia. Look for gaps where the aluminum soffit meets the wall and where fascia boards have pulled away. These are the classic overwintering spots.
• Utility openings. Seal around the dryer vent, the gas line, cable and phone entries, outdoor taps and the air conditioner line set. Use copper mesh or foam for larger holes, which Kentucky recommends.
• Attic and roof vents. Screen them. Penn State recommends number 20 mesh or finer for attics, chimneys and vents.
• Foundation. Seal cracks where the brick meets the foundation and around basement windows.

On a postwar Scarborough bungalow, the soffit line and the old storm windows are usually the weak points. On a back-split, check where the roof lines step down, because the joins between levels leave gaps under the eaves.

What about sprays and traps?

You will see a lot of products sold for ladybugs. Here is where the official and research sources land:

There is also a Canadian wrinkle. Health Canada's page states that no pesticides are currently registered for the control of ladybugs. Any product used on a home in Canada has to be registered by the Pest Management Regulatory Agency for the use on its label. So if someone offers to spray your walls specifically for ladybugs, ask them which product and which label use they are relying on.

When it is worth calling us

For most homes, ladybugs are a vacuum-and-caulk job you can do yourself. A call makes sense when:

• You cannot reach the gaps. Soffits, second-storey trim and roof vents on a back-split are ladder work. Our inspection is free and we will mark every gap we find on the sunny walls.
• You have something else as well. Cluster flies and boxelder bugs use the same walls in the same weeks, and mice follow in November. If the inspection turns up a pest that does have a registered treatment, the pest control cost in Scarborough page lays out the range, with most single treatments between $150 and $450 and mouse work with entry sealing at $200 to $500.
• The beetles are inside a rental. In an apartment or a rented house, gaps in the building envelope are the landlord's to fix. Our guide to whether the landlord is responsible for pest control in Ontario explains how to put the request in writing.

We will not sell you a spray for ladybugs. If the honest answer is a tube of silicone caulk and some screen mesh, that is what you will hear, and you will get a written quote before any sealing work starts.

Ladybugs or something else?

Three fall invaders get mistaken for each other on Scarborough window sills:

All three are covered in our fall pest guide. If you are not sure what you have, send a photo through the form and we will tell you before anyone talks about treatment.

Common questions

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