These predacious diving beetles constitute the largest family (Dytiscidae) of Coleoptera inhabiting water. They are often seen hanging head downward in the water with the tip of the abdomen exposed at the surface. The members of this family are rather oval and flattened in shape. The elytra are usually hard and shiny, often with many punctures. Some of the smaller species are pubescent. The bare filiform antennae are glabrous and have eleven segments. The hind legs are flattened and have five tarsal segments which are fringed with long hairs making them strongly adapted for swimming. The beetles are usually brownish black or olive black in color and sometimes the margin of the thorax and elytra are marked with yellow or more rarely red. Occasional species also have a design in these colors on their back.
Proceedings of the Iowa Academy of Science
©1949 Iowa Academy of Science, Inc.
Schaffner, J. C. and Jaques, H. E.
"A Preliminary List of the Dytiscidae Known to Occur in Iowa,"
Proceedings of the Iowa Academy of Science, 56(1), 397-398.
Available at: https://scholarworks.uni.edu/pias/vol56/iss1/56