When does the Autumn Needle Fly hatch?

August–November, typically 11:00–14:00. It starts from about 4°C, peaks around 8°C and tails off by 17°C.

What flies imitate the Autumn Needle Fly?

Dark Needle, Snipe & Purple, CDC Dark Olive, typically on a #16 hook.

How big is the Autumn Needle Fly?

Adult stage: 5–8mm. That matches a #16 hook.

Stonefly · Aquatic insect

Autumn Needle Fly

Leuctra fusca

Size

5–8mm

Hook size

#16

Hatch window

Season August–NovemberPeak time 11:00–14:00

Water temperature

8° peak

4°17°

How fish feed on it

Mid-July to mid-September, and the egg-laying starts from LATE MORNING rather than at dusk, which catches out anyone treating it as an evening fly. It is far more a river insect than a lake one. Greenhalgh's answer for the egg-laying females is a Snipe and Purple in 14 to 16 — the key autumn stonefly pattern, and one of those flies that looks far too plain to work as well as it does.

Flies that imitate this

Dark Needle

Snipe & Purple

CDC Dark Olive

Ecology

Rivers & stillwaterAlpine riversClean water only

Where you'll find this

British IslesPresent
IberiaPresent
The AlpsPresent
ScandinaviaPresent
Continental EuropePresent
Atlantic fringePresent

Present throughout

Identification

Leuctra fusca is a species of stonefly belonging to the family Leuctridae.