What Fish Eat

Aquatic insects make up the majority of a fish's diet. The four key insect orders (listed first and not including Streamers or Terrestrials) that emerge from streams and lakes are:

 

Sierra Nevada Locals

Pay close attention to these groups of insects when fly fishing in the Sierra Nevada.

 

Salmonflies on Parade

Big Salmonfly A series of photos taken of giant stoneflies ( salmon flies )can be viewed here!

 

Trout Like Nymphs

As nymphs, stoneflies actively crawl along rocky bottoms in search of prey, such as small mayfly nymphs and midge larvae. Their preferred habitat is quick choppy riffles with a substrate of large gravel and cobble. They tend to be most abundant in large low-elevation rivers and moderate-size mountain streams. Only a few species, such as Megarcys signata, occur in high-elevation headwater streams.

Because of the nymph's predacious nature and active hunting style, they end up in stream drift where trout have a chance to see them. A study of trout food preferences in Rocky Mountain streams ranked perlodid nymphs 15th out of 90 different stream insects in availability to trout. So, when these nymphs are present and abundant, they can be well worth imitating.

Rick Hafele

 

Stoneflies

Stoneflies usually spend 10 to 11 months as larvae. However, with different stonefly species it can range from 6 months to 3 years. They typically shed their skin from 6 to 22 times. When the larvae are fully developed, they drift in the stream currents and eventually crawl out of the water to transform into adults.

Golden Stonefly Nymph

The larvae target good emergence sites such as bridge abutments, wood debris, fallen trees, exposed tree roots, aquatic plants, and most often, rocks.

Becoming an Adult Stonefly

Once out of the water, they secure their tarsal claws, split their skin from the head along the thorax, and a teneral adult crawls out.

Adult Salmon Stonefly

Most species of stoneflies transform to adults at night to avoid being eaten by predators. They next move to nearby vegetation such as trees where they wait for their new skin to harden. Adults usually live from 1 to 4 weeks.

Adult Golden Stonefly

Stonefly Larvae

Pattern Name Color Hook Size Thumbnail Image
Bead Head Poxyback Biot Golden Stone White Body # 12
Bead Head Poxyback Biot Golden Stone
Bead Head Wire Wrapped Golden Stone Brown Body with Yellow Wire # 12
Bead Head Wire Wrapped Golden Stone
Hare's Ear Nymph Tan, Brown Body # 16
Hare's Ear Nymph
Kingrey's Little Yellow Stone Nymph Yellow Body # 16
Kingrey's Little Yellow Stone Nymph
Mercer's GB Poxyback Dark Stone Black Body # 16
Mercer's GB Poxyback Dark Stone

Stonefly Adult

Pattern Name Color Hook Size Thumbnail Image
Cat Puke Orange & Brown Body # 8
Adult Giant Stonefly
MacSalmon Orange & Black Body # 8
Salmon Stonefly Fly Pattern
Stimulator Fire Orange Body # 12
Stimulator
Yellow Humpy Yellow Body # 12
Yellow Humpy

Photo of October Caddisfly by P. Michael Carl © The Ecological Angler