In Hawaii, certain moths have adapted to take advantage of hoary bats' longer-range social calls. By adjusting their hearing downward, the moths can detect bats from farther away, allowing them to take earlier evasive action. These moths can afford such a low-frequency specialization only because there are no other bat species to avoid in Hawaii. Many moths that hear an approaching bat try to escape by dropping to the ground or by flying into foliage. Hawaiian hoary bats are fast, tenacious hunters that sometimes pursue moths to within six inches of the ground, making longer-distance hearing quite advantageous.
Moths are the hoary bat's most common prey.
Other common prey include beetles, flies, crickets, stink bugs, and burrower bugs. The Hawaiian hoary bat is known to feed heavily on damp wood termites, which are highly destructive to wooden buildings. Several researchers have also found hoary bats eating mosquitoes. This practice is probably not typical, though the stomach of one hoary bat in Oregon was found half full of these tiny insects. Since hoary bats rank among the largest and highest flying of North American bats, it is unlikely they would bother to pursue such small and maneuverable insects when larger ones are available.