RIFFLE BEETLES OF WISCONSIN (COLEOPTERA, DRYOPIDAE, ELMIDAE, LUTROCHIDAE, PSEPHENIDAE) WITH NOTES ON DISTRIBUTION, HABITAT, AND IDENTIFICATION

Twenty-four species of Elmidae, three species of Psephenidae, two species of Dryopidae, and one species of Lutrochidae were represented among 33,351 riffle beetles that were identified from Wisconsin. Almost all were found in streams, but some inhabited wave-swept lake margins and spring-ponds. Adults and larvae of eight species were collected almost exclusively from submerged, decaying wood, while those of most other species inhabited rock or gravel substrates, especially in stream riffles, and only occasionally were found in wood; adults of three species of Dubiraphia were found also on macrophytes. The presence of Stenelmis antennalis, S. fuscata, and S. knobeli in Wisconsin represents significant range extensions.