Best Bet for Spring Trout

One of the first mayflies to emerge in the spring are blue winged olives (Baetis sp.). These mayflies tend to have two or three generations per season depending on how fertile and warm the stream is. When fishing the nymphs remember that it will be the larger mature nymphs that are getting ready to emerge that will be the most active. A simple olive Hare's Ear type pattern is all that is needed, but if you're fishing a fly larger than size 16 your fly is too big.

Baetis sp. nymphs - the larger nymph in the foreground will be ready to emerge in a week or so,

the smaller one in the back still has some growing to do and will emerge in mid-summer. 

Most Baetis nymphs emerge mid-stream on the surface but a few species will crawl out along the stream margin.

Baetis sp. nymph getting ready to emerge.

Not all blue winged olive duns are olive - some come in shades of tan or rusty-brown.

Baetis sp. dun almost fully emerged