Caddisfly · Order Trichoptera
Caddisfly
Also called Sedge, Caddis, Elk hair.
Short answer
Caddisflies are moth-like insects with tent-shaped wings that hatch from spring through autumn across almost every trout stream in North America. Trout eat the larva, the pupa and the adult, and the pupa rising to the surface is the stage most often missed. Hook sizes 12 to 20.
What a caddisfly is
Caddisflies are an entire order of insects rather than one hatch, and in most trout streams they outnumber mayflies several times over. The adult looks like a small moth, with wings folded in a tent over its back, and it flutters and skitters rather than drifting serenely like a mayfly. The larvae live in the stream for most of the year, many of them building portable cases out of sand, gravel or twigs. The stage that catches the most fish and gets fished the least is the pupa, which swims to the surface in a bubble of gas and is eaten on the way up by trout that look, from the bank, as if they are taking adults.
- Hook size
- Hook sizes 12 to 20, most often 14 to 16
- Colour
- Tan, brown, olive, grey and occasionally bright green, depending on species and river
The stages trout eat
- Larva
- Lives in the stream all year, often in a case of sand or twigs. A green or cream larva fished deep works anywhere.
- Pupa
- The most productive and most neglected stage. Rises through the water column in a gas bubble, and trout intercept it there.
- Adult
- Tent-winged, skittering, and active at dusk. The elk hair caddis is the pattern the world uses.
- Egg-laying female
- Dives or crawls underwater to lay eggs. A wet caddis fished on the swing imitates it exactly.
When does the caddisfly hatch?
| When | What is happening |
|---|---|
| April – May | The Mother's Day caddis on western rivers, and the Grannom in the East. Dense, brief and sometimes overwhelming. |
| June – July | Steady emergence on most rivers, best in the last two hours of light. |
| August – September | Evening hatches continue, and the egg-laying flights at dusk can be better than the hatch. |
| October | The October caddis in the West — a big orange insect, size 8 to 10, and the last good dry fly of the year. |
Emergence dates move with latitude, altitude and the weather of a given year. Treat these windows as a shape, not a diary, and check a local report before you travel.
Where it matters
Everywhere. If a river holds trout it holds caddis. The Mother's Day caddis on Montana's Yellowstone, the Grannom in Pennsylvania, the Arkansas River caddis hatch that climbs upstream through May, and the October caddis of the Pacific Northwest are the named ones, but the unnamed background hatch is constant.
Fly fishing in Colorado Fly fishing in Montana Fly fishing in Pennsylvania Fly fishing in Oregon Fly fishing in Arkansas
How to fish it
Fish the pupa during the hatch and the adult at dusk. A soft-hackle swung across and down imitates a rising pupa better than anything more complicated, and it catches fish while everyone else is casting dries at splashy rises. When trout are taking adults, remember that caddis move — a twitch or a short skate at the end of the drift will often trigger a fish that ignored the dead drift.
- A splashy rise usually means pupae, not adults. Swing a soft-hackle through it.
- Caddis skitter. A deliberate twitch at the end of the drift is not cheating.
- The best caddis fishing is in the last hour of light, and most people have gone home.
Flies that imitate it
Each of these is a card in the deck, and each has a full page in Our Fly-brary.
Keep reading
- Dry fly vs nymph — which stage to fish, and when
- Why trout refuse your fly — usually the wrong stage, not the wrong pattern
- Best time of day to fly fish — the daily logic behind the table above
- Our Fly-brary — every fly in the deck, explained