March Browns on the Lower Yuba

The March Brown Mayfly is sort of a ghost hatch on the Lower Yuba. some years you'd never know they exist and the next year there they are. This is one of the years that they are happening. How do we know. The best indication is when you spot clouds of dancing male march brown spinners hovering over the water. They are the big ones. The females are smaller. You will often see these spinners bouncing above the runs. The females The spinners that you see hatched a few days earlier.

The duns hatch and hang around the bushes and trees for a few days and then they molt into sexually mature spinners.  Their colors darken, their wings become much clearer and in the case of the males their tails and forelegs elongate. They mate and the females return and drop their eggs.

March Brown Nymphs

The march brown mayfly typically arrives with the onset of spring. It is a "clinger" mayfly and clings tenaciously to rocks in the fast water. Does the name march brown mean that the fly hatches in March, not necessarily. In our river it is more of an April event and the conditions need top be just right. Big spring storms with high flows happen and you'll never know there are march browns in the river.

In our river the march brown nymphs are very dark brown and almost black. That doesn't mean that they are available to our trout very often. They have the ability to cling to rocks like no other. They also tend to hide under and in the crevices during daylight hours. They venture out at dark They are adapted to stay out of harms way. But when the nymphs become mature they sport large dark wing pads they start to get restless as they begin to contemplate emergence. They start to migrate to slower water along the edges. Guess what, they loose they foothold and end up in the drift. This is when fishing march brown nymphs are the most effective, basically prior to emergence.