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Sow Bug

Sow bugs are freshwater isopods — the aquatic cousins of the terrestrial pill bug or “roly-poly.” Like scuds, they’re crustaceans rather than insects, but they fish like nymphs: subsurface, year-round.

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Scud

Scuds aren’t insects — they’re freshwater amphipod crustaceans, distantly related to ocean shrimp.

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Midge

Midges are the year-round food source — the bug that keeps trout feeding through January and February when nothing else is hatching.

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Crayfish

Crayfish are big-meal targets — when a trout (especially a brown trout) eats a crayfish, that’s a serious calorie haul.

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Spruce Moth

The spruce moth is a mid-summer terrestrial event that some Western rivers see and others don’t — it depends on the conifer outbreak cycle.

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Grasshopper (Hopper)

When summer hits its hottest stretch and aquatic hatches thin out, hoppers become the menu.

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Ant

Ants are the second-most-important terrestrial after grasshoppers — and on small streams, in technical low-water conditions, or during a flying-ant swarm, they’re the more important of the two.

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October Caddis

The October Caddis is the West’s biggest caddis hatch and one of the most important fall events for trout fishermen.

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Skwala

The skwala is the Western fly fisher’s first true dry-fly hatch of the year.

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Salmonfly

The salmonfly is the iconic Rocky Mountain hatch — a 2–3 inch dark stonefly whose emergence triggers some of the year’s most aggressive trout feeding.

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Nemoura

Nemouras (and the nemourid family generally) are small dark stoneflies that emerge in early spring, often a few weeks ahead of the skwala.

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Golden Stone

The golden stone is the salmonfly’s smaller cousin. Adults sport a yellow-tan to golden-amber body with darker wings, roughly 1 to 1.5 inches long.

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Trico (Tricorythodes)

The Trico is one of the smallest hatchable mayflies, a black-bodied, white-winged miniature whose summer-morning emergence and spinner fall draw trout to the surface in clouds of feeding fish.

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PMD (Pale Morning Dun)

The Pale Morning Dun is the dominant summer mayfly across the West.

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March Brown

The March Brown is the second major mayfly hatch of the spring season, typically following BWOs and overlapping with skwalas.

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Mahogany Dun

The Mahogany Dun is a small-to-medium fall mayfly with a deep reddish-brown body, color so distinctive it gives the species its common name.

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Hecuba

The Hecuba is one of the largest mayflies of the fall, a russet-brown to mahogany-bodied dun that emerges just as October caddis activity is winding down.

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Green Drake

The Green Drake is one of the year’s most-anticipated dry-fly hatches in the West.

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Gray Drake

The Gray Drake is a large, slate-gray mayfly that overlaps with the Western Green Drake but is more often fished as a spinner than a dun.