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Bats

Little (L) and Big (R) brown bats Little brown bat Mexican free-tailed bat
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What they look like
Batman got it right—you’re most likely to see bat silhouettes in the sky at dawn and dusk. Most bats in the Northeast are brown with 9-12 inch wingspans and bodies 3-5 inches long. (A bat folded up at rest, hanging from its toes, looks surprisingly small, though.) Got lots in your attic? Note their poop, aka guano, which piles up beneath their hang-out spots.

Where they live
Bats like to have a few options. During summer days they hide in your attic, behind your shutters, or in your barn. Bats can get through crevices as small as ¼” wide by 1 ½” long or holes ½” by ½”. At night they’re mainly on the wing and hunting, but now and then they relax a bit under your porch or breezeway. In winter they hibernate, usually migrating to a cave, mine, or rock crevice.

What they do

Bats do lots of good, eating kazillions of mosquitoes and other insects. Their guano can grow mold, though—not good to breathe. If you find a bat in your room, it’s probably as shocked as you are—sometimes the young get lost when learning to fly in late summer. If a bat gets trapped in a room or you find it on the ground, call a professional wildlife control officer—you want to be cautious about the potential for rabies. Don’t take offense if a bat swoops at you outside—it’s just catching a pesky mosquito. Don’t worry about it getting stuck in your hair. Go about your business and it’ll go about its.

How to deal with bats

Bats are good to have around. Putting up bat boxes on your property will give them a place to hang besides your attic. But if bats are in your belfry, call a professional. They’ll work with you to close up crevices and holes that let bats in. Closing up all holes in summer could trap baby bats inside—best to wait till late fall, when they’ve all moved out on their own.

Learn more

Beasts Begone, A Practitioner's Guide to IPM in Buildings

Contact your local Cornell Cooperative Extension office.

... and search our database of online publications.