Bat species that consume insects include mosquitoes in their diet, but the idea that bats are specialized mosquito-eating machines is a common misconception. These aerial hunters are insectivores, meaning their diet is composed entirely of flying arthropods. While bats contribute to natural pest control, their impact on localized mosquito populations is complex. They play an important role in the nighttime ecosystem by reducing vast numbers of flying insects, which benefits agriculture and human health.
Dietary Habits of Insectivorous Bats
Insectivorous bats are opportunistic feeders, capturing whatever flying insects are most abundant and energetically profitable. The majority of their diet consists of larger, soft-bodied insects like moths and hard-shelled insects such as beetles. These larger prey items offer a higher caloric return for the energy a bat expends during the hunt.
Mosquitoes provide significantly less energy per capture, making them less desirable than moths or beetles. Consequently, mosquitoes typically represent only a small fraction of a bat’s overall food intake, especially when larger insects are plentiful. However, when mosquito density is very high, such as near standing water, their sheer abundance can make them a worthwhile target.
Smaller bat species are more likely to consume mosquitoes than larger ones, due to differences in their echolocation capabilities and metabolic needs. Larger bats often use lower-frequency echolocation, which is less effective at detecting small prey. Conversely, smaller bats require less total energy and can more easily meet their needs by focusing on large quantities of smaller prey.
Effectiveness of Bats as Mosquito Predators
The often-cited figure of a bat consuming thousands of mosquitoes per night generally refers to the total volume of small, mosquito-sized insects consumed. A single bat can consume an amount of food equal to 50% to 100% of its own body weight nightly, especially nursing mothers. This feeding rate translates to a massive number of insects.
Research shows that smaller species, like the Little Brown Bat (Myotis lucifugus), are highly effective at hunting mosquitoes when they are abundant. A study involving Little Brown Bats and Big Brown Bats (Eptesicus fuscus) found that both species consumed more mosquitoes than previously recognized, including nine species known to carry West Nile virus. Estimates suggest a small bat would need to consume approximately 600 to 660 mosquitoes to meet its nightly energy demands if its diet were composed solely of them.
While a single bat may catch up to 1,000 small insects in an hour, the true impact comes from large colonies. A major colony of Southeastern Bats, for example, has been calculated to consume over 15 tons of mosquitoes annually. Bats are effective predators, but their impact on human-biting mosquito populations is not always precisely localized, as they forage across large areas.
Attracting Bats for Natural Pest Management
Individuals interested in leveraging bats for pest management can attract them by providing suitable roosting habitat, most commonly through the installation of a bat house. Bat houses should be constructed from rough, unpainted wood, as bats need a textured surface to cling to. The interior roosting chambers must be narrow, typically between three-quarters of an inch and one inch wide.
Location and temperature control are the most important factors for attracting a colony, particularly a maternity colony where females raise their young. The bat house should be mounted on a building or pole, rather than a tree, and placed at a height of 12 to 20 feet off the ground. It must receive at least six hours of direct sunlight daily to maintain the necessary internal temperature, ideally between 80°F and 100°F.
The exterior color of the house should be chosen based on the local climate to help regulate heat, with darker colors preferred in cooler regions to absorb solar energy. While a bat house can successfully host a large colony, bats forage widely and may not focus exclusively on a single backyard’s mosquito problem. Providing a nearby water source can also increase the likelihood of occupancy.