These photos supplement pages 97-103 of the Guide to Aquatic Invertebrates of the Upper Midwest. Information on the biology of Mesoveliidae can be found on page 100. Mesoveliidae can be confused with Gerridae and Veliidae. Mesoveliidae can be distinguished by how the claws on the forelegs insert on at the apex. In addition, Mesoveliidae have dark spines on their femurs.