Dryopidae
Dryopidae is a family of beetles, commonly named long-toed water beetles, in the superfamily Byrrhoidea. It was described by Gustaf Johan Billberg in 1820. Description. Long-toed water beetles are named for their extended claws. Adults have dense hairs, which allow the beetles to breathe while underwater. The flight muscles of the females weaken as they age. When the pupae complete the imago stage of their life cycle, they move towards running water, and may be attracted to lights. Despite being referred to as aquatic insects, the beetles are unable to swim, clinging to detritus that float. All  long-toed water beetles feed on plants that are in the water, but the larvae also prey on small animals and most of them are terrestrial. "Stygoparnus" is the only genus in the family in which both the larvae and adults are aquatic. Genera of the family closely resemble riffle beetles, but the antennae are different from the long-toed water beetles, looking similar to clubs. Habitat. Members of this family are found on every continent, except Antarctica and Australia, being more common in the tropics. In 2005, a possible fossilized specimen of Dryopidae was found in the Crato Formation  by entomologists David Grimaldi and Michael S. Engel. Beetles that have water as a habitat, including long-toed water beetles, can help show the quality of fresh water. Education. Essay questions about the long-toed water beetles were placed in a teacher's manual about insects, written by entomologist Matthew Cooke and published in 1884.