Wikipedia
Lutrochidae is a family of water beetles sometimes known as "travertine beetles", since in North America they are common in springs and streams depositing travertine.
They are distinguished by their ovate bodies, 2-6 mm long and yellowish in color, and short antennae in which the first two antennomeres are longer than the others. The larvae are elongate, 4-10 mm in length, with short but well-developed legs.
Both adults and larvae are found in fast-moving water, feeding on algae and wood.
The family is known only from the New World, and consists of 12 species in a single genus Lutrochus, although it is likely that the genus will be divided upon review. The genus has been variously classified under Dryopidae and Limnichidae, but has more recently been given its own family.