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 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.
This beetles 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 or Ground Beetles. Behavior is also reminiscent of Tiger Beetles: hunting by running down prey.
The larvae of this species pass through three instars, and like the adults they live where soil meets water.
West Virginia's two species are E. ruscarius (pictured) and E. californicus. The latter is less frequently encountered, and generally a golden color.
Right: Mating pair of Elaphrus ruscarius
