The Urban Hatch: A Deep Dive Into the Insects of the Spokane River

Written by Teeming Streams Fly Fishing Adventures

There are rivers where the hatches announce themselves in towering clouds of mayflies, in caddis blizzards, in stoneflies crawling over every branch.
And then there’s the Spokane River, where the river keeps its insect life tucked beneath basalt shelves, where rises look like secrets, and where the bugs that matter most often go unnoticed unless you’ve trained your eyes to catch the smallest flicker of life on the water’s surface.

Fishing the Spokane’s urban reach—from the thunder of the falls to the canyon-feel downstream—is an act of paying attention. The river is not generous with its cues. It is not loud. But it is alive in a way that feels almost improbable in the middle of a city.

The insects of this reach are subtle, tough, and opportunistic—just like the trout that feed on them.

Below is an in-depth exploration of the hatches that shape this fishery, season by season, bug by bug, mood by mood.

WINTER – The Cold, Clear Technical Season (December–February)

Winter on the Spokane is for anglers who are willing to slow down enough to see what the river is actually doing.

Midges (Year-round, but especially winter)

Midges are the heartbeat of the urban river.

You won’t see clouds of adults like on spring creeks.
Instead, you’ll see:

• tiny clusters on foam lines

• near-invisible dimples from surface-feeding trout

• shucks collecting in back-eddies

• subtle, rhythmic sips around midstream boulders

A winter midge hatch here is so delicate that you often mistake fish for surface tension changes until you train your eye for the shape of a trout’s rise.

Patterns that matter:

• Midge emergers (size 18–22)

• Tiny black or olive adults

• Suspended pupa patterns

Winter Stones (Capniids)

Small, black winter stoneflies crawl along frozen banks and dance across the water in little skitters that look like misplaced punctuation marks.
Most anglers never notice them.
Trout absolutely do.

A small, dark nymph drifted slow and low can produce surprisingly aggressive winter eats.

EARLY SPRING – The First Hint of Life (March–April)

As the canyon walls thaw and the days stretch longer, the Spokane begins to shift. The river is still cold, still technical, still subtle—but patterns emerge.

Early Brown Stoneflies (Nemourids)

These small stones appear before any real mayfly activity. They crawl onto rocks in the warming afternoons and occasionally skitter across slow seams near the bank.

Their importance is not in the adults you see (you’ll see few).
It’s in the nymphs drifting:

• through pocket water

• down riffles

• along ledges

• behind basalt blocks

If you want to understand early-season subsurface fishing here, understand these stoneflies.

Early-season Caddis Larvae

They are not hatching yet, but they’re active.
Green rock worms (Rhyacophila) and net-spinners (Hydropsyche) drive much of the early-season nymphing success.

When the river is still 38–42 degrees, caddis larvae rule.

MID–LATE SPRING – The River Wakes (April–June)

If there is a moment when the Spokane’s insect world finally shows itself, it’s late spring.

Caddis (May–June, then again later in fall)

The first true hatch that the average angler will notice.

But even then, it’s subtle.
You won’t see clouds of bugs.
You’ll see:

• erratic fluttering near banks

• birds working riffles

• trout rising in slow, deliberate patterns

The river’s structure—deep slots, fast tongues, turbulence under basalt—breaks up surface activity. The hatch is there; it’s just distributed across complex water.

Important caddis:

• Tan caddis

• Olive caddis

• Spotted sedges

Trout often key more on the emergence than the adults.

March Browns (April–May)

Not prolific, but meaningful.

The Spokane’s March Browns don’t behave like Clark Fork or Yakima bugs:

• emerges occur in pulses

• fish feed subsurface for 90% of it

• surface eats are slow sips, not splashy rises

If you see a rise that looks like a leaf falling?
It’s probably a feeding trout.

EARLY SUMMER – PMDs, PEDs & the Start of the Topwater Season (June–July)

This is when the Spokane starts to feel like a “real” dry-fly river—if you know where and when to look.

PMDs (June–July)

They are the most important early-summer mayfly here.

But the PMD hatch on the Spokane is rarely dramatic:

• duns appear sparsely

• fish feed intermittently

• rises are spread across entire runs

You’re looking for:

• subtle head-and-tail rises

• shadow lines near banks

• slow glides in early-evening light

The Spokane rewards perfect drifts during PMDs.
“Close enough” does not cut it.

PEDs – Pale Evening Duns

These are the hatch that surprises people new to the river.

In the right light—soft, warm, slightly filtered—the PED hatch can produce gorgeous topwater moments in the long, green glides downstream of the TJ Meenach area or near Downriver Park.

Trout rise with deliberate confidence, surfacing like they’re tasting each fly before committing.

MID–LATE SUMMER – Ants, Beetles, Caddis & Subtle Stones (July–September)

Summer on the Spokane is not hopper-driven the way the Yakima or Clark Fork can be.
Instead, its summer hatches are about:

• subtle terrestrials

• predictable evening caddis

• hidden stonefly activity in riffles

Terrestrials (July–September)

Small ants and beetles matter more on the Spokane than classic hoppers.

Why?

• narrow riparian zone

• fewer grassy banks

• more vertical basalt

• more trees → more ant falls

Some of the best summer dry-fly eats of the year come from:

• cinnamon ants

• flying ants

• small black beetles

When fish refuse everything else, a tiny ant placed tight to a slow seam can save the day.

Evening Caddis (July–August)

Not thick.
But consistent.

Trout feed:

• in back-eddies

• along soft shelves

• near overhanging brush

• at the tails of long glides

It’s not a blanket hatch.
It’s a rhythm—a quiet, almost musical evening routine the river falls into.

Yellow Sallies

These little stoneflies appear in pulses throughout summer and produce:

• quick subsurface grabs

• fast riffle eats

• opportunistic behavior from redbands

Sallies are the hidden engine of summer feeding.

FALL – The Peak of Spokane Dry-Fly Fishing (September–October)

Autumn is when the Spokane reveals its best self.
Cool nights.
Stable flows.
Clear water.
Elegant hatches.

Blue-Winged Olives

The signature fall hatch.

Overcast days turn the river into a slow-motion ballet of:

• tiny olives

• soft rise rings

• long, gentle head-and-tail eats

This hatch is the most technical and the most rewarding.

Mahogany Duns

Larger than BWOs.
More visible.
More rhythmic.

The Mahogany hatch is the Spokane’s most underappreciated event.
Fish eat them confidently, especially:

• along slow seams

• in soft inside bends

• in the shadows of basalt walls

October Caddis

Sparse, but powerful.

Redbands show a different side when these big orange caddis flutter at dusk.
Most eats are not sips—they are detonations.

Why Spokane Hatches Are So Subtle—and So Rewarding

Because this river is:

• urban

• canyoned

• cold

• incredibly complex hydraulically

• rich in biomass despite its setting

• dominated by wild redband trout that feed with terrifying efficiency

The Spokane doesn’t show you its hatches.
You must discover them.

Every rise is a clue.
Every fluttering caddis is a hint.
Every subtle swirl near a basalt ledge is the river whispering its secrets.

Anglers who learn to read these signs feel a connection to the Spokane that few understand.
It’s a river that rewards attention, patience, humility, and curiosity.

The Spokane may be urban.
But its insect world is wild—and it speaks to anyone willing to listen.