Western March Brown

Family: Heptagenlidae

Genus: Rhithrogena

Life Cycle: incomplete

Three Life Stages: egg, nymph, adult cycle which includes 2 phases: dun and spinner

Emergence: March-May

Clinger Mayfly Group

Nymph

Body Description

Antennae: 2 short

Head: head is wider than the abdomen

Eyes: large

Gills: large and overlapping under the abdomen forming a suction cup to help cling and move about the rocks in the fast currents

Tails: 3

Legs: 6

Body Color: olive-brown to brown

Mobility: slow swimming and floating; they drift long distances before they go to the surface

Size: 8-12mm

Hook Size: 10-14

Live in the faster current of riffles and runs in the rocks.

Dun

Body Description

Antennae: 2 short

Head: flat

Eyes: large

Wings: 2 sets, grayish and highly marked with dark brown mottling; distinguish from callibaetis because March Browns have prominent 2 ^nd wing while callibaetis do not

Tails: 2

Legs: 6

Body Color: top is shades of brown; bottom is shades of tan

Size: 8-12mm

Hook Size: 10-14

Spinner

Body Description

Wings: clear and heavily veined

Body Color: light to medium brown

After emerging into spinners they mate and return to the water to lay their eggs but don’t normally provide a fishable spinner fall.