What are those black and red bugs crawling all over Fort Collins?

Jacy Marmaduke
The Coloradoan
A boxelder bug crawls on a leaf.

The bug that seems to be swarming Fort Collins has a name.

Meet the boxelder bug, the black and red critter that has probably taken a liking to your home, your office, your car — we could go on.

The good news is boxelder bugs are harmless. The bad news — for those not fond of creepy crawlers — is they're not moving out of your living spaces anytime soon.

Here's everything you ever wanted to know about your antennaed roommates.

1. What are they?

Boxelder bugs are half-inch long, winged insects with black bodies and red or orange markings. They're called boxelder bugs because they're often found around boxelder trees. Although they're native to the western United States, they can be found across the country and in Canada. They can fly but quite enjoy crawling around walls and surfaces.

2. Why am I seeing so many?

It's boxelder migration season. Boxelder bugs hang out in trees during the summer. Around fall they head indoors to survive the winter. The bugs crawl inside building cracks and crevices, which is why you'll often spot them near windows, according to the University of Minnesota extension office.  

Boxelder bugs are attracted to warmth, so you'll see more of them in buildings with large southern or western exposure and buildings that stand taller than their neighbors, according to the extension office.

You also might be seeing a lot of boxelder bugs because you have a lot of boxelder trees in your neighborhood. Fort Collins is home to thousands of boxelder trees, which are a type of maple tree. A 2015 study found that the city's roughly 30,000 maple trees account for about 7 percent of all trees.

3. Do they bite?

No. But "their piercing-sucking mouthparts can occasionally puncture skin, causing a slight irritation and producing a red spot similar to a mosquito bite," according to PestWorld.org

4. What can I do about them?

Your best bet is sealing your home's cracks and crevices, installing door sweeps and repairing holes in door and window screens. Visit the Colorado State University extension website for tips on handling a boxelder bug infestation.

5. When are they going away?

By spring, boxelder bugs head back outside to enjoy warmer weather.

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