When does the American March Brown hatch?

March–May, typically 11:00–15:00. It starts from about 8°C, peaks around 12°C and tails off by 17°C.

What flies imitate the American March Brown?

American March Brown, March Brown Sparkle Dun, Adams Parachute, typically on a #14–12 hook.

Spinner stage: 8–11mm. That matches a #14–12 hook.

Mayfly · Aquatic insect

Rhithrogena morrisoni

Size

8–11mm

Hook size

#14–12

Hatch window

Season March–MayPeak time 11:00–15:00

Water temperature

12° peak

8°17°

How fish feed on it

Thin and rarely significant this early in the year.

Flies that imitate this

American March Brown

March Brown Sparkle Dun

Adams Parachute

Ecology

Rivers & stillwaterFreestone rivers

Where you'll find this

Present throughout