Species Hydrophilus triangularis

Giant Black Water Beetle

32-40 mm

Large, shiny black with olive tinge. Underside with prominent spine (prosternal process). Similar to the usually smaller H. (Dibolocelus) ovatus. H. triangluaris is more oblong, H. ovatus more oval. H. ovatus is more common southward. The two are keyed based on the prosternum, divided into two lobes in H. ovatus, undivided (entire) in H. triangularis--see print references for details (1) (2).

Much of North America: Quebec to Florida, west to British Columbia, California.

Weedy ponds, lakes. Comes to lights.

April-August (South Carolina)

Hydrophilus ovatus

Compare also large predaceous diving beetles (Dytiscidae), such as Dytiscus, Cybister.

Dillon, pp. 165-166, plate XVII, fig. 145--prosternal process (1)

Ciegler, p. 125, fig. 6.72 (2)

Papp, pp. 67-68, figs. 202-204, larva, adult, pupa (3)

White, p. 106, fig. 37 (4)

Arnett et al., p. 120, fig. 301 (5)

Powell and Hogue, p. 269, fig. 344 (6)

Salsbury, p. 172--photo (7)

Brimley, p. 133 (8)

Aquatic Hydrophilidae of Mississippi--illustration

Canadian Biodiversity

God of Insects--excellent photo