About three weeks ago, bats started getting into my room when I leave the window open. At first I thought it was just one, but I've seen like four different ones now. I don't want to kill them or anything, I just want them to go somewhere else. Is there something I can put on the windows or some kind of sound they don't like?
My house had something similar happen, and what worked was just closing the window after dark, or leaving it open only a bit with a mosquito net fitted properly. The bats come in looking for insects flying around inside, so if you reduce the bugs getting in with the net, they'll go somewhere else; those ultrasonic things and stuff like that almost never work from what I've seen.
What actually works is sealing the entry points, because ultrasonic sounds and flashing lights are basically a total myth. If four different bats are already getting in, it means there are cracks or gaps in window frames or blinds that you can't see with the naked eye. The mosquito netting that someone mentioned above is fine, but it has to have no gaps, because those little critters squeeze through any crack. Another option is to install foam strips or weatherstripping around windows and doors for fall/winter, so you close those gaps without giving up ventilation during the day.
Bats almost always look for places to spend the night because they're hungry for insects, so if four different ones come in over three weeks, there's probably something attracting them besides just the open window. Check if you have plants or lights near your bedroom that attract flying insects, because where there's easy food they'll keep coming back. A properly installed mosquito screen is your best defense, but it has to be without any gaps - those bugs find every single crack.
What's worth mentioning is that these animals usually have an entry pattern. Watch what exact time they come in and specifically where they're getting through. If it's always the same window at the same time, it's because they know that route. Besides sealing it up tight, try turning off the lights in that room an hour or two before you go to bed, because bats see worse without light and they're more likely to go somewhere else.
Those ultrasonic devices they sell in some places promise results but honestly they don't work like they advertise. You're just throwing money away. The real solution is physical: screen with no holes, sealed entrances, and no lights attracting the insects they eat. If they keep trying anyway, maybe you need to check if there are cracks in the walls or ceiling you're not seeing at first glance.
Forget about ultrasonic repellents and flashing lights - that's money down the drain. What you actually need is to be realistic: if four different bats have found your room in three weeks, it's because your window is basically a highway for them. It's not just that they're looking for a place to sleep, but there's probably a ton of insects flying around your house (attracted by the lights, the humidity, whatever), and the bats know it.
The practical trick that's missing from all that is checking not just the windows, but also tiny cracks around frames, pipes coming in, holes in the blinds, or those weird gaps between furniture and the wall. Bats squeeze through minuscule openings. While you're at it, the obvious stuff works: if you want nighttime ventilation, put up an actual window screen, pulled tight with no gaps. Any old mesh won't cut it; it has to be intact. And consider turning off the inside lights when you have the windows open, or at least switch them to warm-colored bulbs that attract fewer insects.
If they get in anyway, open the window all the way so they can leave on their own (they usually head toward the light) and close it as soon as they're gone. The plan is to make life uncomfortable for them without any violence: no insects, no easy entry, no reason to stick around. Eventually they'll look somewhere else.
Log into answer.
