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.[3]
When the
pupae complete the
imago stage of their life cycle, they move towards running water, and may be attracted to lights.[3]
Despite being referred to as
aquatic insects, the beetles are unable to swim,[2] clinging to
detritus that float. All long-toed water beetles feed on plants that are in the water, but the
larvae generally are
terrestrial, and at least some also feed on plant matter. Stygoparnus is the only genus in the family in which both the larvae and adults are aquatic.[2][3][4][5]
Genera of the family closely resemble
riffle beetles, but the
antennae are different from the long-toed water beetles, looking similar to clubs.[6]
Habitat
Members of this family are found on every continent, except Antarctica and Australia, being more common in the
tropics.[7] In 2005, a possible fossilized specimen of Dryopidae was found in the
Crato Formation by entomologists
David Grimaldi and
Michael S. Engel.[4]
Beetles that have water as a habitat, including long-toed water beetles, can help show the quality of
fresh water.[8]
^Kodada, Ján, Jäch, Manfred A. and Čiampor Jr., Fedor. "Dryopidae Bilberg, 1820 (1817): Coleoptera, Beetles". Handbook of Zoology Online, edited by Andreas Schmidt-Rhaesa. Berlin, Boston: De Gruyter, 2016.