Alternate name: Giant Black Water Beetle
Family: Hydrophilidae, Water Scavenger Beetles view all from this family
Description 1 3/8-1 1/2" (34-38 mm). Elongate oval, strongly convex above, almost flat below. Brown, gray or shiny black; legs reddish black. Short antennae clubbed, inconspicuous. Long slender labial palps held forward, easily mistaken for antennae. Spine under middle of thorax extends forward to fit a cup-shaped cavity.
Food Decaying remains of aquatic animals or small live animals.
Life Cycle Female deposits 120-140 yellow eggs in silken cocoonlike egg case with a hornlike "mast." The case, 7/8-1" (22-24 mm) across and 5/8" (15 mm) deep, is left to float or attached to some underwater object. Larvae feed underwater. In late summer fully grown larvae leave water to prepare pupal cells in moist earth. Adults emerge in less than 2 weeks and return to water. 1-2 generations a year.
Habitat Ponds and slow streams.
Range Throughout North America.
Discussion Some adults creep under litter on land to overwinter; others are active under ice all winter and live more than 1 year. On summer nights these insects often leave water and fly about, drawn to artificial lights. The widespread Giant Water Scavenger (H. triangularis), 1 3/8-1 1/2" (34-38 mm), is black with dark olive reflections.
