The unseasonably warm weather in Montreal this week has brought with it blue skies — as well as swarms of biting, invasive ladybugs.

“One weekend in the fall, the air is thick with ladybugs. Like, you can see only ladybugs in the air for miles. Millions and millions and millions,” Nicola Miller of Mont St-Hilaire told CBC Daybreak on Wednesday.

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The Asian lady beetle is also in Ottawa. This is a photo of the species' aggregation behaviour.

She said she’s encountered them each fall in the three years she’s lived in the area.

At this time of year, Miller said, she gets pelted by ladybugs when she steps out of the house.

And it’s not just an autumn nuisance, she said. They’ve been burrowing into the nooks and crannies of her home for the winter, coming out when her family lights a fire and warms up the house.

She said she’s been bitten a number of times, and while it doesn’t hurt quite as much as a bee sting, it still hurts.

Caralee Salomon, a Dollard-des-Ormeaux resident, said she's been catching them in her house for days. 

"I was pelted with these ladybugs each time I stepped outside over the weekend and when I went out for a walk yesterday, she told CBC News.

"Over the course of the day and well into the night, I was catching them in my bedroom and disposing of them down the toilet. I thought they were gone, but I've caught three of them so far this morning and can hear more bouncing around somewhere in the room."

'It's hard to love these things'

Christopher Buddle, an entomologist and associate professor at McGill University, said the species is called the Asian lady beetle and it’s been in southern Quebec for between 10 and 15 years.

It was brought to North America intentionally decades ago to help control crop-eating aphids, and has been moving further north and east thanks to warmer temperatures.

"I must admit, it’s hard to love these things," Buddle said.

He said the aggregation behaviour — swarming, in layman’s terms — is "kind of like a bit of a horror movie at times." 

They also produce a smelly substance that is especially potent when crushed, and fight hard to get into people's homes for winter hibernation and reproduction purposes.

Buddle said these are not your typical ladybugs. The region’s native species — the nine-spotted — has largely disappeared by now, he said. What is left — the Asian lady beetle and the seven-spotted — are both imported from overseas.

The Asian lady beetle is hard to control. Buddle said the best defences are to find the holes they’re entering your house by and cover them up immediately, as well as to vacuum the ones you find up — but make sure to empty the vacuum canister outside.