Helophoridae inhabit the margins of flowing waters and are not commonly encountered in wetlands. Adult Helophorus lack swimming hairs on their hind legs, and can be identified by the 5 wavy grooves running lengthwise on the pronotum. The last 3 segments of their antennae are enlarged relative to the remaining segments and form a small club.

Helophorus larvae have 10 abdominal segments (10th is small), and each abdominal segment has several large plates on top; two segmented tails that have 2 or 3 segments extend from the tip of the last abdominal segment (not from segment 9 as in some similar families).