Western March Brown Emerger

The March Brown also known as the Western March Brown nymph is a clinger that is the first mayfly to hatch in many western trout streams. They inhibit the fast waters of riffles and runs of the streams.  However, on occasions they can be found in the slower to moderately moving water. Their hatches are usually not bountiful and may be short and dispersed. The duns hatch sporadically for a few hours and are seldom concentrated.

The early season hatches usually occur during the warmest part of the day, while the summer hatches usually occur during mid-day and the late summer or early fall hatches usually occur during the warmest part of the day. As with the nymph imitations, the emerging March Brown imitations should be tried before the dun imitation. However, if you see the hatching in progress, switch to the dun imitation. It takes trial and error to determine if the trout prefer them in the surface or well below the surface, as it depends on the season and the water conditions.