05/22/2007 Southeastern shore of Lake Mills before breaching of Glines Canyon Dam, Olympic National Park, Washington
05/16/2008 Southeastern shore of Lake Mills before breaching of Glines Canyon Dam, Olympic National Park, Washington
04/27/2009 Railroad Bridge Park, Sequim, WA
05/28/2009 Southeastern shore of Lake Mills before breaching of Glines Canyon Dam, Olympic National Park, Washington
06/12/2010 Southeastern shore of Lake Mills before breaching of Glines Canyon Dam, Olympic National Park, Washington
05/18/2008 Railroad Bridge Park, Sequim, WA
Specimen collected Southeastern shore of Lake Mills before breaching of Glines Canyon Dam, Olympic National Park, Washington
This species occurs on sandy, silty, and gravelly banks of medium to large streams all over western North America. Before the Glines Canyon dam was removed in 2011, the Elwha River formed a delta as it flowed into Lake Mills in Olympic National Park. We noticed this population on a sand bank at the far southern end of Lake Mills. Thanks to David H. Kavanaugh, Senior Curator of Entomology at the California Academy of Sciences, for the identification from a photo.
While Opisthius, with its large eyes, looks somewhat like a small tiger beetle (both are members of the family Carabidae), its jaws are much smaller. These beetles move somewhat like Tiger Beetles, but fly less and are easier to approach. On the same sandbank, I observed and photographed two species of tiger beetles.