Bats! Here’s Why So Many Are Flying Around Northern Illinois

If you've spent any time outside on recent Northern Illinois evenings, you've probably noticed them too.

Just after sunset, dark shapes begin darting and swooping through neighborhoods, parks, and backyards. While it might look like a scene from a Halloween movie, what you're actually seeing is one of nature's most effective pest-control crews hard at work.

Illinois is home to several species of bats, including the Big Brown Bat, Little Brown Bat, Eastern Red Bat, Hoary Bat, and Silver-haired Bat. Of those, Big Brown Bats are among the most commonly seen in Northern Illinois and are known for roosting in buildings, barns, and sometimes attics.

And they're all really active right now in mid-June of 2026.

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Right Now Is A Particularly Busy Time For Northern Illinois' Bats

This time of year is especially active for bats. Summer insect populations are booming, and bats are taking full advantage of the buffet. A single bat can consume hundreds, and sometimes thousands, of insects in a single night, including mosquitoes, moths, beetles, and other flying pests. The next time you see bats zig-zagging across the evening sky, they're likely hunting for their dinner.

When winter arrives, some Illinois bats hibernate in caves, abandoned mines, and protected structures, while others migrate south. During hibernation, a bat's heart rate and metabolism slow dramatically, allowing it to survive months with little or no food.

Bats are also pretty fascinating because they're the only mammals capable of true flight. They navigate and hunt using echolocation, emitting high-frequency sounds and interpreting the returning echoes to locate insects in complete darkness. Some species can live 20 years or longer, making them surprisingly long-lived for such small animals.

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If You're Going To Have A Discussion About Bats, You've Got To Mention Rabies

While bats are associated with most human rabies cases in the United States, it's important to remember that fewer than one percent of wild bats are believed to carry the disease.

The concern stems from the fact that bat bites can be extremely small and sometimes go unnoticed. Experts recommend never handling a bat, especially one that appears sick, injured, or unusually tame.

For most of us, though, the bats zipping through our yards at dusk aren't something to be afraid of. They're simply one of Northern Illinois' most beneficial and misunderstood wild neighbors, helping keep summertime insect populations in check one mosquito at a time.

And no, they won't get tangled in your hair.