Duns. Emergers. Sedges. Ephemeroptera. When it comes to the little aquatic insects that make up much of a trout’s diet, the terminology that fly anglers throw around can be pretty confusing. It’s doubly so if you’re new to fly (or trout) fishing and just trying to select the right fly to use. But to make a reasonable guess at what’s in the river, all you really need is a little knowledge about what the fish eat.
The three most common aquatic insects that trout—plus bass, carp, panfish and sometimes even walleye—love to munch are mayflies, caddisflies and stoneflies. Coming in a variety of sizes, colours and shapes, complete with complex life cycles, they’ve inspired literally thousands of effective imitations. My choices tend toward patterns that are more universal and generally imitative, with lifelike movement in the water. So with just a couple of fly boxes, I feel equipped to fish for trout almost anywhere in Canada. Here’s a thumbnail guide to the big three aquatic insects, along with choice imitations and strategies for making them appear lifelike.