Numbers
68 species in 4 genera in North America (
nearctica.com)
200 species in 5 genera worldwide (
Tree of Life)
Identification
body convex dorsally, broadly oval or boat-shaped (with pointed posterior) and brownish or reddish-yellow with dark spots; hind coxae very long, flat, and broad, covering much of the ventral surface of the abdomen - but this feature is not visible in dorsal photos
Habitat
larvae and adults are aquatic, preferring standing water such as large ponds that have no shade and plentiful algae
Food
larvae feed entirely on algae, either the filamentous forms such as Spirogyra, or macroalgae such as Chara
adults feed on oligochaet worms, small crustaceans, hydrozoans, the eggs of midges, and algae
Life Cycle
overwinters as an adult in permanent standing water
Remarks
adults periodically come to the water surface for air; atmospheric oxygen is captured in bubbles and stored in three places - under the wings, at the tail, and under the large coxal plates - allowing the beetle to breathe underwater for long periods
adults swim slowly and clumsily by "shuffling" (moving their legs alternately, rather than in unison like predaceous diving beetles do)
Print References
American Beetles, Vol. 1, Chapter 8
(1)Internet References
live adult and larva images of the genera
Haliplus and
Peltodytes, plus other info (U. of Michigan)
live adult and larva images plus other info (West Chester U., Pennsylvania)
closeup photo of large coxal plate in genus
Haliplus (Aquatic Beetle Conservation, Germany)
preserved adult images plus description, classification, biology, etc. (Tree of Life)
