Elaphrus ruscarius

Shore Ground Beetle

Elaphrus ruscarius, Marsh Ground Beetle photo

Family: Carabidae

Subfamily: Elaphrinae

Length: 7 - 10 mm


Beetles in the genus Elaphrus are recognized by their small size, metallic coloration, large eyes, and the elaborately sculpted elytra. Elaphrus ruscarius features green metallic color on the elytra and pronotum, with elytral punctures that are colored blue or violet.

Beetles of this species will be found running up and down the shores of rivers and large creeks, preying on various tiny arthropods.

Specialists in Ground Beetles believe the immediate ancestor of Elaphrus lived in Siberia and Alaska in the Late Cretaceous, and radiated from there and gave rise to the several current species. Most Elaphrus species still make their homes in northern climes, but Elaphrus ruscarius is found as far south as northern Florida and eastern Texas.

Elaphrus ruscarius, Shore Ground Beetle photo from West Virginia

This beetle’s metallic green coloration and striking markings remind us of tiny Tiger Beetles, and indeed they are in the same family as Tiger Beetles, the Carabidae (the ground beetles). Behavior is also reminiscent of Tiger Beetles: hunting by running down prey.

The larvae of Elaphrus ruscarius pass through three instars, and like the adults they live where soil meets water.

Photo data (upper photo): 22 March 2009. Wetland 5 miles east of Buckhannon, Upshur County, West Virginia.

Photo data (lower two photos): 9 May 2005. Stonecoal Wildlife Management Area, Upshur County, West Virginia. Along the right fork of Stonecoal Creek.

Elaphrus ruscarius mating pair, Shore Ground Beetles