Mayfly · Tricorythodes
Trico
Also called Tricorythodes, White-winged black, Trike.
Short answer
The trico is a tiny black mayfly with white wings, hook size 20 to 26, that hatches at dawn in late summer and falls as a spinner within a few hours. The spinner fall is dense enough to look like smoke over the water, and it produces the most selective dry-fly fishing of the year.
What a trico is
Tricos are among the smallest mayflies anglers bother to imitate, and they make up for it with numbers. They hatch overnight and at first light, mate in dense swarms above the river through the early morning, and fall spent onto the surface in such quantity that the water can look dusted. The whole cycle is over by mid-morning. The fishing is unusual in that the hatch barely matters — what you are fishing is the spinner fall, on flies of size 22 and smaller, to trout lined up in feeding lanes eating one insect a second and refusing anything that drifts a fraction wrong.
- Hook size
- Hook sizes 20 to 26
- Colour
- Black body, white wings; males and females differ, with females often olive-bodied
The stages trout eat
- Nymph
- Tiny and rarely imitated directly. Not where the fishing is.
- Dun
- Hatches in the dark and at first light. Brief, and usually over before anglers arrive.
- Spinner
- The whole point. Spent black bodies and white wings flat in the film, in enormous numbers.
- Cluster
- Spinners often fall in clumps. A fly tied to imitate two or three at once can beat a single.
When does the trico hatch?
| When | What is happening |
|---|---|
| July | The first falls begin on the warmer rivers, usually mid to late morning. |
| August | Peak, and the falls move earlier — dawn to about nine, finished before most anglers have had breakfast. |
| September | Still strong, starting later again as mornings cool. Often the most comfortable month to fish it. |
| October | Tailing off, and overlapping with the autumn Baetis. |
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
Spring creeks and tailwaters above all — Silver Creek, the Missouri, the Bighorn, the Delaware, the Driftless creeks of Wisconsin and Minnesota, and the limestone water of Pennsylvania. The Idaho, Montana, Pennsylvania, Wisconsin and Minnesota pages all name it.
Fly fishing in Idaho Fly fishing in Montana Fly fishing in Pennsylvania Fly fishing in Wisconsin Fly fishing in Minnesota
How to fish it
Get there at dawn and accept the tippet. 6X is not enough on most trico water; 7X and a size 22 is a normal rig, and the leader needs to be long. Because the fish eat on a rhythm, cast to where the fish will be rather than where it rose. If you cannot see your fly — and you will not — fish a slightly larger visible dry with the trico on a short dropper behind it.
- You are fishing the spinner fall, not the hatch. Be on the water before sunrise.
- Use a visible dry as an indicator with the trico trailing eighteen inches behind.
- When the fall is thickest the fishing is hardest. The best minutes are at the start and the end.
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