Little Yellow Stonefly

Other Common Names: Yellow sally, early orange stonefly, western yellow stonefly
Scientific Names: family Perlodidae, especially the genus Isoperla

Some rivers have significant populations of little yellow stoneflies. Nymphs live in riffles and rocky runs with moderate to fast flows. They are often knocked loose and drift in the current, so a nymph imitation can be productive when dead-drifted through riffles and runs.

At maturity, nymphs migrate to slower water, then crawl onto shore. Migration times are another nymph-fishing opportunity, especially near dusk because that is the major "drive time" for the nymphs.

Adults emerge on out-of-the-water objects such as rocks and tree trunks. Adults are active in the warm part of the day. Some end up on the water, so it is worthwhile to cast a dry fly near bankside vegetation. Odds are, a trout will be close at hand waiting for errant little yellow stoneflies to stumble onto the water and drift to them.

Females return to the water to lay their eggs by dipping their abdomen in the riffles. Many are taken by trout at this time, and others end up spent on the water and drift into collecting areas, such as backeddies. This creates more dry fly fishing--one in the riffles with a heavily-hackled fly, and one in the quieter water where less hackle is needed.

While most little yellow stonefly adults hatch out on land, there is a species that emerges in the water like a mayfly.

Characteristics

NYMPH COLOR: Mottled tan/brown/light yellow.

ADULT SIZE: 7-16 mm

ADULT COLOR: Yellow to light brown body, head; yellows can be very bright, almost fluorescent. Wings light tan to yellow.

OTHER CHARACTERISTICS: Nymph--no external gill filaments. Adult--well-developed tails.

 

Click on the fly name to see the pattern. Click on the presentation to learn how to do it.

STAGE PATTERN SIZE/
COLOR
PRESENTATION WHERE
Nymph Hares Ear 8-14
Pale yellow, brown
indicator, tight line Riffles, runs; just below these
Adult Stimulator 10-16
Yellow, brown, yellow-brown
standard dry fly Bankwater near foilage
Elk Hair Caddis 10-16
Yellow, brown, yellow-brown
standard dry fly Bankwater near foilage
Clarks Stonefly 10-16
Yellow, brown, yellow-brown
standard dry fly Bankwater near foilage
Parachute Hares Ear 10-16
Yellow, brown, yellow-brown
standard dry fly Bankwater near foilage
Egg-layer Stimulator 10-16
Yellow, brown, yellow-brown
standard dry fly Riffles, moderate-fast runs, backeddies, current seam
Elk Hair Caddis 10-16
Yellow, brown, yellow-brown
standard dry fly Riffles, moderate-fast runs, backeddies, current seams
Clarks Stonefly 10-16
Yellow, brown, yellow-brown
standard dry fly Riffles, moderate-fast runs, backeddies, current seams
Parachute Hares Ear 10-16
Yellow, brown, yellow-brown
standard dry fly Riffles, moderate-fast runs, backeddies, current seams