This spring has certainly been one of the wettest I can remember. Plenty of fish have been caught but most have on nymphs and streamers. My preference has always been to take trout feeding on the surface and conditions for dry fly fishing are improving significantly.
There is an anatomy to a hatch. Most activity is centered around aquatic insects such as mayflies, caddis flies or occasionally stoneflies. Mayfly nymphs begin to stir about one to two hours before the visible hatch commences. This is the emerger stage. It is not uncommon to see trout flashing under the surface feeding on the insects as they struggle to begin their odyssey upward to the surface. Caddis flies hatch more rapidly but they still have an emergence stage: the pupa. I will cover caddis in more detail in the next report. Stoneflies most often seem to crawl out of the water to hatch so they are important to the trout in their egg laying stage.
Once the mayflies hatch they are known as "Duns" scientifically this is the "Sub-Imago"