When does the Yellow Sally hatch?

May–August, typically 12:00–16:00. It starts from about 8°C, peaks around 14°C and tails off by 19°C.

What flies imitate the Yellow Sally?

Yellow Sally, Partridge & Yellow, Yellow Humpy, Stimulator, typically on a #14–12 hook.

How big is the Yellow Sally?

Adult stage: 9–12mm. That matches a #14–12 hook.

Stonefly · Aquatic insect

Yellow Sally

Isoperla grammatica

Size

9–12mm

Hook size

#14–12

Hatch window

Season May–AugustPeak time 12:00–16:00

Water temperature

14° peak

8°19°

How fish feed on it

Unusually for a British fly, this one wants MIDDAY SUN in high summer — bright and hot, when conventional wisdom says go home. Sparse until late June and then steady through the warm part of the day. And as with every stonefly, the nymph crawls out to emerge, so it is the egg-laying female returning to the water that you are actually imitating, not a hatch.

Flies that imitate this

Yellow Sally

Partridge & Yellow

Yellow Humpy

Stimulator

Ecology

Rivers & stillwaterSpate riversAlpine riversClean water only

Where you'll find this

British IslesPresent
IberiaPresent
The AlpsPresent
ScandinaviaPresent
Continental EuropePresent
Atlantic fringePresent
North America — WestPresent
North America — EastPresent
East AsiaPresent
New ZealandPresent
PatagoniaPresent

Present throughout