Chasing the salmonfly hatch: timing, water and flies

For a few weeks each year, two-inch stoneflies crawl out of Western rivers and big trout lose their caution. The salmonfly hatch is the closest thing fly fishing has to a holiday. Here’s how to time it, where to look, and what to tie on.

What a salmonfly is

Salmonflies are the largest stoneflies in North America. The nymphs live for several years among the rocks of fast, cold, well-oxygenated rivers, which makes them a year-round food source for trout.

When the hatch happens

On most Western rivers the hatch arrives in late spring or early summer, usually somewhere between late May and early July depending on elevation and the year’s snowpack.

Before the hatch: fish the nymph

In the weeks before adults appear, nymphs migrate toward the banks and trout feed on them heavily.

During the hatch: bang the banks

Once adults are flying, fish a big dry tight to the banks, under overhanging willows and along grassy edges.

After the peak: don’t quit too soon

The days just after the peak are often better, when fish are still keyed on big bugs but the river isn’t covered in them.