Species Cybister fimbriolatus

Giant Diving Beetle (1). "Fringed Diving Beetle" might be appropriate.

Species name from Latin, fimbria fringed. Fimbriate in entomology refers to a "structure displaying marginal setae of irregular length". (2) This refers to the metatarsi, presumably.

26-33 mm

Large diving beetle, elytra with yellow margin. Similar to Dytiscus species, but metatarsal claws different. (See guide for genus.) Elytra and pronotum smooth in male. Unique structure on male protarsi, used for grasping female during mating. Dytiscus male has similar structure, but differing in details--two large disks are obvious. White, fig. 33, and Papp (1), figs. 178, 179 illustrate this well (3). Female Cybister has five furrows on pronotum. Male Cybister has, apparently, two rows of punctures on each elytron, lacking in Dytiscus (3).

Eastern and central North America. Only member of its genus in southeast.

Aquatic: ponds, usually deep water. Comes to lights.

Much of year in south. February-September, November-December (South Carolina). March, May, July, September-October (North Carolina).

Preys on aquatic insects, fish, etc.

Seems to have two periods of activity per year, based on reported collection dates.

Dytiscus species. Compare also, Hydrophilus, a Giant Water Scavenger Beetle.

Papp, p. 62, figs. 177-178 (1)

Gordh, entry for fimbriate (2)

White, fig. 33, has illustration of male protarsus, comparing with Dytiscus. (3)

Dillon, pp. 153-154, Plate XVI (4)

Ciegler, p. 88, figs. 5, 102 describes and illustrates C. fimbriolatus. (5)

Salsbury, p. 170--photo (6)

Brimley, p. 132 (7)

Evans, plate 31--color photo of specimen (8)

Swan and Papp, p. 351, fig. 595--also shows male tarsus (9)

North Carolina State University lists only C. fimbriolatus from that state--59 pinned.