Insects are being spotted in massive numbers clustering in the windows of Ontario homes, looking to find their way inside.

And while many of these tiny ladybugs may look like the endangered nine-spotted lady beetle native to Ontario, there's a good chance that the ones trying to work their way into your homes this time of year are introduced pest species like the seven-spotted lady beetle or the Asian lady beetle.

The former species are your standard ladybugs recognizable by their crimson red shells and telltale spots, but it's the yellow and orange-coloured Asian lady beetle — also known by the scientific name of Harmonia axyridis — that can really cause upset in your place of residence.

Ladybug/Asian Lady Beetles Infestation in My Apartment - What Should I Do?
byu/Queasy-Material8961 inlondonontario

The species first started spreading in North America after it was introduced in the U.S. as part of a plan to control aphid populations in the 1970s. After a half-century, the species has now largely displaced native populations of similar insects in the coccinellid family.

Aside from their range in colouration that includes yellow, orange and red, the Asian lady beetle can be distinguished from others by the white 'M' shaped marking on its thorax.

In the event that you missed these telltale characteristics, the Asian lady beetle has two more rude surprises to deter anyone who makes the mistake of handling it.

Ladybugs are completely taking over Toronto homes and here's why 🐞https://t.co/Ls2EivWB1N #Toronto #LadyBugs

— blogTO (@blogTO) October 24, 2023

This species is perhaps best known for its bite, which, while not of any medical significance to humans, can catch people by surprise if they think they are handling a harmless ladybug. But the bite isn't even a defense mechanism, and is likely just a response to our salty skin being read as a delicious snack by the tiny predators.

What is a defense mechanism, though, is the Asian lady beetles' ability to "reflex bleed" a fluid called hemolymph when handled by unsuspecting humans.

I can speak from firsthand experience when I say that this stuff smells awful — kind of like the smell of decomposing leaves at the edge of a pond. If you're unfortunate enough to get any on your clothes, expect a stain.

Some people have a more acute reaction to the substance, and allergic reactions have been documented.

So, you can see why it's such a big concern when clusters of these bugs find their way into your home. And that's an issue homeowners struggle with every fall as masses of these critters seek out warm places to stow away for the coming winter.

People in Toronto have insect infestations but they aren't likely ladybugs https://t.co/ee6bQkYxvh #Toronto

— blogTO (@blogTO) November 11, 2021

Rebecca Flanagan of Armour Pest Control tells blogTO, that "during the warmer months, we advise clients to seal any gaps or cracks to prevent the insects from penetrating inside."

"If the issue persists, applying an insecticide with a residual to the exterior of the home would add additional protection."

However, Flanagan notes that with temperatures rapidly dropping, the risk of invasion is "not as much of an issue."