Pros and Cons of Having a Bat Box?

June 11, 2016 2:54 PM

Hello! We, thankfully, don't have much of a mosquito problem, but are considering installing a bat box just for general insect management. Anybody on MeFi have any experience with one? If you do, what do you like about it? What could you do without? I have two concerns: 1) Bats getting into the house 2) A collection of nasty bat poop under the bat box That's pretty much as far as I've gone in my research. No further snowflakes. Thank you!
posted by funfunfun to Home & Garden (11 answers total)

Hello! I didn't need a bat box in my old place, as some would take up roost in my patio roof. They are wonderful mosquito eaters.

As for worries about them getting into the house: mostly they won't want to. If they do, you won't hear them (unless they bump into something in their panic) and they're gonna want to get out just as much as you want them to get out. So open a door/window, stay calm and quiet and let them orient themselves back outdoors. Source: grew up in the countryside and often had bats in my childhood bedroom. They're very polite fellows.

Guano: it makes an excellent fertilizer!
posted by fraula at 3:10 PM on June 11, 2016 [11 favorites]

I just built one!

We've had bats living in our shutters for a few years now, so I decided to make some nicer accommodations for them this year.

We generally have at least 50 or 60 bats around (probably more--there's a very bat friendly area where I can't see), and none of them have come inside.

As far as the poop, it sort of accumulates on the ledge outside the house, but it's not a big deal at all. It's kind of like mouse poop, hard little pellets, so you can just sweep it off or wait for the winds to pick up and blow it away.

So far, I don't think we have many bats living in the house I built them, but I think it might be a suboptimal location.
posted by ernielundquist at 3:12 PM on June 11, 2016 [3 favorites]

Yeah, bat poop is surprisingly inoffensive-- dry little pellets smaller than rice grains, no appreciable smell and not even that much of it.
posted by The otter lady at 3:25 PM on June 11, 2016 [1 favorite]

The consensus seems to be that, while bats do eat mosquitoes, they don't eat enough of them to make much of a difference. Also, they would rather eat one big, fat June bug than a hundred mosquitoes-much less work.
this
this

"Do bats serve as an effective mosquito control?
Recently the public has shown increased interest in the value of insectivorous species of bats in controlling mosquitoes. Although untested lately, this is not a new idea. During the 1920's several bat towers were constructed near San Antonio, Texas, in order to help control malarial mosquitoes. Mosquito populations were not affected and the project was discontinued. Bats in temperate areas of the world are almost exclusively insectivorous. Food items identified in their diet are primarily beetles, wasps, and moths. Mosquitoes have comprised less than 1% of gut contents of wild caught bats in all studies to date. Bats tend to be opportunistic feeders. They do not appear to specialize on particular types of insects, but will feed on whatever food source presents itself. Large, concentrated populations of mosquitoes could provide adequate nutrition in the absence of alternative food. However, a moth provides much more nutritional value per capture than a mosquito. M.D. Tuttle, a world authority on bats, is often quoted for his anecdotal report that bats effectively controlled mosquito populations at a popular resort in New York State. While there is no doubt that bats have probably played a visible, if not prominent, role in reducing the mosquito problems in many areas, the natural abatement of mosquito populations is an extremely complex process to study, comprising poorly known ecological relationships. Tuttle attempts to underscore the bats role by citing an experiment in which bats released into a laboratory room filled with mosquitoes caught up to 10 mosquitoes per minute. He extrapolated this value to 600 mosquitoes per hour. Thus, a colony of 500 bats could consume over a quarter of a million mosquitoes per hour. Impressive numbers indeed, but singularly unrealistic when based upon a study where bats were confined in a room with mosquitoes as their only food source. There is no question that bats eat mosquitoes, but to utilize them as the sole measure of control would be folly indeed, particularly considering the capacity of both mosquitoes and bats to transmit diseases."
posted by H21 at 3:28 PM on June 11, 2016 [2 favorites]

Effective mosquito control or not, bats are awesome and it's cool that you want to have some living near your house! I love watching bats making passes back and forth over the backyard on summer evenings.

I've had bats, and bat boxes, lots of times in the past. Mostly you don't even notice the bats; the only time they're active that you're likely to see them is after the sun has gone down but before the sky is dark enough to obscure their silhouettes. I've never noticed their poop (unlike bird poop) or had one get in the house. I've known them to get in houses, but by all accounts all they want to do is get out again. Usually they get in by accident.

What I guess I'm saying is that I can think of no downsides to having a bat box. The main upside is that you get to feel good about making a home for some interesting and helpful animals, plus the entertainment they provide on summer evenings. Go for it!
posted by Anticipation Of A New Lover's Arrival, The at 5:01 PM on June 11, 2016 [8 favorites]

It's a pretty cool thing to sit out in your yard on a summer evening just around dusk and watch them come out and zoom through your yard. Not a bad way to enjoy a cold beverage on a sweet summer night.
posted by raisingsand at 5:06 PM on June 11, 2016 [2 favorites]

I was in a hurry when I answered before, but it occurs to me that I should point you at some resources, because apparently, there are a lot of bat house kits and things that aren't particularly habitable or even necessarily safe for bats.

Bat Conservation International has lots of information about building your own bat houses, and they also certify premade bat houses, if you'd rather buy one.

There is also a whole forum about building bat houses, and the members seem pretty helpful and knowledgeable.

I didn't have much space to work with when I built mine, but I made a fairly large one (it could probably house about 200 bats) with hand tools and a minimal investment in materials. And I just finished this pretty recently, so if you decide you want to build and have any questions, feel free to message me. It's still fairly fresh in my head so I can probably point you to resources for other questions.
posted by ernielundquist at 7:41 PM on June 11, 2016 [4 favorites]

The only con that comes to my mind is that bats can carry rabies, so you want to be careful in case one ends up inside your house. The risk is small, though, so this would not keep me from getting a bat box.
posted by amf at 3:32 AM on June 12, 2016 [2 favorites]

Unfortunately, I have bats who come in my house all the time...older house with cedar beam cathedral ceilings. Despite trying to caulk up every little nook and cranny, they come in. I have a bat house, too. They do absolutely defecate before entering...but their droppings are dry and mouse sized, so not traumatic to deal with. If they're not already visiting you inside, they won't start because if this I think. Mine come in and go out by morning. It used to bother me, but I've gotten used to it. The cat? Not such a fan of the swoopy flying things.
posted by OneSmartMonkey at 1:47 PM on June 12, 2016

Sorry to be off topic for the question, but OneSmartMonkey, if you often sleep where bats have access to you, you should get rabies vaccine. Their bites can be so small you wouldn't notice them. CDC says postexposure prophylaxis (i.e., rabies vaccine after exposure to rabies, which still works because of the time it takes rabies to travel to the brain) "can be considered" after a single instance of a person sleeping in a room where a bat was discovered. If it's a routine thing for you, I think the prudent thing to do is to get vaccinated. It will protect you for years.
posted by lakeroon at 9:47 PM on June 12, 2016

I'm late to the party, but nth the idea that bats are wonderful and I very much hope you decide to provide them a bat house. Wanted to add that if you do, please include a pup catcher to help any bat mothers or babies that fall out - the sanctuary Bat World, Inc., has instructions on how to make one (you should also visit their webcams which are OMG adorable).

Good luck - I hope you're hosting a happy colony in short order!
posted by DingoMutt at 5:44 AM on June 14, 2016