Little Yellow Sally Stone Fly, Isoperia Grammatica

Your #1 online resource for fly fishing education and knowledge

Little Yellow Sally Stone Fly,

Isoperia Grammatica

The Yellow Sally Stone fly is considered by many fly anglers as the most important Stonefly on the river based solely their abundance.  The Yellow Sally Stonefly is a rare Stonefly in that it’s emergence begins, on many rivers of the West, in late May and will continue to emerge or hatch the rest of the summer.  Yellow Sally nymphs are not exceptionally large mainly in the size 10 range and will live in highly oxygenated water.  These guys live among and under rocks in fast moving water.  As they grow in size they become very carnivorous as they will move around and hunt smaller game.  The nymph is of medium size and will have a deep gold or light brown segmented body.  Good fly imitations will range in color and will often be accompanied by a gold or black bead.

The Yellow Sally has an incomplete metamorphosis and when it’s time for the nymph to emerge into an adult will crawl out of the river to emerge as an adult.  They will crawl on the streamside vegetation or rocks.  Many times while fly fishing you can find their empty exoskeletons dried up on streamside rocks which is a good sign for you to be on the visual alert.  The Yellow Sally’s emergence or hatch is a nocturnal one and may last a good portion of the evening.  Once trout catch on they will move closer to shore in an effort to get in on the action.  Once they crawl out onto the bank they will search out a spot to break out of their nymphal schuck and emerge as adults.  Their bodies take on a bright yellow color and they can be anywhere from 1/3 to ½ inch long.

Yellow Sally Stoneflies can live up to or exceed a couple of weeks before mating and laying their eggs back into the river. They are active throughout the summer depending on the river you are fishing.  In many cases trout will key in on them whenever they are about.  When the hatches are minimal or you are between hatches tie on a Yellow Sally and your luck just might change.