For decades, bat biologists have debated the extent to which bats prey on, and potentially reduce mosquito populations. However, recent research suggests bats may be eating far more mosquitoes than yet suspected. Amy Wray and associates (2018) relied on newly refined techniques that provide greater sensitivity.
In their paper, titled Incidence and taxonomic richness of mosquitoes in the diets of little brown and big brown bats, they reported that these common species eat a greater variety of mosquitoes, and catch them more frequently than previously suspected.
They tested guano samples from 22 locations in a range of habitats, across the State of Wisconsin, from May 17 through July 29. Seventy-two percent of little brown myotis (Myotis lucifugus) samples contained mosquitoes representing 15 species, more than twice as many as big brown bats (Eptesicus fuscus). But even the larger big brown bats, previously thought to feed mostly on beetles and moths evidenced mosquito-eating in 33 percent of samples. Mosquito-eating remained constant throughout the active season in big brown bats but declined slightly in little browns.