Insect Encyclopedia
March Brown
Rhithrogena spp.
Heptageniidae
MayflyHook #12-1410-14 mm body
Peak activity
JanFebMarAprMayJunJulAugSepOctNovDec
Nymph
Slender body with gills along the abdomen; clings to rocks in current.
Adult
Upright sail-like wings; two or three tail filaments.
Habitat & hatch
Found in rivers, tailwaters, and spring creeks, most commonly in riffles and runs. Bottom-dwelling nymph; emerger mid-column; adult on surface film. Often associated with gravel and cobble. Nymphs rise through the water column; duns ride the surface before flying to vegetation.
Timing
Individual emergence windows typically last 3 to 14 days. Strongest surface activity occurs around midday, and the afternoon.
Sources
- AB Fish Report synthesis from peer-reviewed Alberta and western North America literature.