Bats do not carry bed bugs, as is often stated, though some of the parasites occasionally found on them can be mistaken for bed bugs by those unfamiliar with external parasites. The normal position of most bats at rest is to hang head downward, though a few rest on horizontal surfaces in caves and elsewhere. Occasionally, fruit bats, while scrambling about in trees, get into a head-upward position. When a bat is hanging head downward in an elevated position, it is very easy for it to take flight by merely letting go, dropping, and spreading the wings. Photographs of bats in flight reveal that their legs work in unison with the wings, just as swimmers use their legs and arms at the same time.
Some bats pick insects off foliage or even off the ground.
Probably all bats require more water or moist food than do other mammals of comparable weight, because their wings have such great evaporation surfaces in comparison with their weight. When catching insects in flight, a bat uses the tail and wing membranes to prevent the escape of its prey. When it has an insect in its mouth on which it does not have a firm grip, the bat spreads its legs out and forward, so that the membrane is spread into an excellent lap, and bends the head forward into this apron. Thus, it keeps the insect under restraint while it manipulates it about in its mouth and renders it helpless. Bats do this in flight, when hanging up, or on a level surface.