Bats walk a fine line between seeming like cute and cuddly petite pets and dark creatures of the night. On the one hand, there’s no denying bats look like adorable little fuzzballs. On the other hand, we all know that bats feed on some pretty unsavory things. Even setting aside the old idea that bats feed on blood, bats still eat a great many mosquitoes.
This may, on the surface of it, seem to make sense. After all, mosquitos also suck blood, so by eating mosquitos, you would imagine bats would be able to get their fill as well. Still, that doesn’t mean that there aren’t a whole host of different questions buzzing around bats’ mosquito diet.
An Overview of Bats and Mosquitos
Bats do indeed eat mosquitos regularly, as collaborative research by the United States Forest Service and Wisconsin Department of Natural Resources found that all little and at least 60% of big brown bat sites studied had at least one mosquito present, suggesting they’re a ready source of food. Still, mosquitos are hardly the be-all eat-all for bats. Bats will eat mosquitos when they are present and plentiful, as is the case in Sweden. However, in other areas, where mosquitos are less plentiful, bats will eat all manner of other things, especially insects.
Still, if you do live in an area where there are plenty of mosquitos, keeping and attracting bats to eat mosquitoes may seem like an attractive option. They get to eat a bunch of mosquitos, and you get to be rid of those blood-sucking disease-carrying pests.
But do bats control mosquitoes in terms of actually significantly reducing their population in the area in which they are kept? Just how many mosquitos do they eat? Browse around online and you’ll find “1,000 mosquitos per day” is a popular estimate, but is there actually any hard evidence to back that up? Fuzziness may be fine when it comes to bats’ fuzzy coats, but it isn’t what you want when it comes to answering the all-important question of “how many mosquitoes does a bat eat per day?”
You don’t want to be disappointed in a bat’s mosquito-control powers, you don’t want to underfeed your bat, and you certainly don’t want to risk overwhelming it with more mosquitos than it can handle.
So, where do the facts stand on each of these important bat-mosquito points?
Dissecting the 1,000 Mosquito Claim
The source of this claim seems to be that it’s physically possible for bats to eat 10 in 60 seconds. Still, just because it may be possible for you to eat three large cheese and pepperoni pizzas in a single day, that doesn’t mean we do so – or that we’d be healthy if we did regularly to that degree. Unsurprisingly, the hard evidence for bats eating such a huge amount of mosquitos every day, therefore, is slim to none.
People just seem to have extrapolated from that figure from this fact and a 1960 study that found they ate a great deal of mosquitos in the enclosed echo chamber. However, this study wasn’t focused on bats’ feeding habits, but their echolocation abilities, and if you trapped someone in a room with nothing but pizza, they might eat a lot of it, but that doesn’t mean that much pizza is or should be part of their everyday diet.
Bats and Mosquito Control
Still, while that 1,000 mosquito per day claim may be extremely dubious, that hasn’t stopped people hyping bats’ potential to eat a lot of mosquitos under the right conditions. Those dubious reports have only grown bigger in recent years, with reports of social media claims that bats can eat 10,000 mosquitos per night – 10 times the amount we’ve already said is unrealistic for most bats in most everyday circumstances. The New York Department of Environmental Conservation modifies the 1,000 mosquito claim to “mosquitoes and other flying insects,” making it clearer that bats don’t specifically target mosquitos but are largely simply looking for a good insect-based meal.
Still, when mosquitos are part of a bats’ everyday diet, they do often eat the kind of mosquitos that are most dangerous for us. A study in the Journal of Mammalogy found that at 22 roosts of big and little brown bats the bats ate nine species of mosquitos that carry West Nile Virus.
However, that doesn’t mean that bats’ reputation as mosquito control is bulletproof – far from it. In fact, members of the Florida and America Mosquito Control Associations disagreed with the idea that bats are effective mosquito control, citing the fact that they prefer beetles and that mosquitos were more of an occasional snack than a staple of their diet. What’s more, we have been trying to use bats as mosquito control for some time, and have known the vastly limited and dubious effects of that claim for at least a century. In the 1920s, bat towers for mosquito control were erected in San Antonio, only for the project to be abandoned because it was not effective.
One of the most commonly-cited sources arguing in favor of bats as mosquito control is the 2009 Resikind-Wund study claiming long-eared bats had a significant impact on mosquito populations and larvae. However, a 2013 study of five Australian bat species directly challenged the extent of these claims, arguing that it had not accounted for variables such as the satiation of the bats in question or how many mosquitos versus other available insects.
There is no question that bats eat mosquitos and, under the right conditions, can eat a lot of them. The big question is whether those “right conditions” can or do exist in such a way for them to serve as effective mosquito control, and so far the weight of evidence seems to lean against that. While theoretically possible, under normal conditions bats do not eat anywhere close to 1,000 mosquitos per night.
In short, you shouldn’t rely on bats alone to combat a mosquito problem.
Still, if you’re interested in keeping them, there’s no harm in allowing them to feast and potentially reaping a nice fringe reward of a potentially-lower mosquito count some days.