When does the Autumn Dun hatch?

August–October, typically 14:00–19:00. It starts from about 9°C, peaks around 14°C and tails off by 20°C.

How big is the Autumn Dun?

Spinner stage: 10–14mm. That matches a #12–10 hook.

Mayfly · Aquatic insect

Autumn Dun

Q: What flies imitate the Autumn Dun?

March Brown, Greenwell's Glory, Pheasant Tail Spinner, Klinkhåmer Special, typically on a #12–10 hook.

Ecdyonurus dispar

Size

10–14mm

Hook size

#12–10

Hatch window

Season August–OctoberPeak time 14:00–19:00

Water temperature

14° peak

9°20°

How fish feed on it

The females lay by resting on stones and pushing their abdomens below the surface, which keeps them concentrated around structure rather than spread over the flats. Greenhalgh's observation is the useful one: trout on the autumn spinner will ignore smaller flies — iron blues, purple spinners — available at the very same moment. Match the big one.

Flies that imitate this

March Brown

Greenwell's Glory

Pheasant Tail Spinner

Klinkhåmer Special

Ecology

Rivers & stillwaterSpate rivers

Where you'll find this

British IslesCommon
The AlpsCommon
ScandinaviaCommon
Atlantic fringeCommon
Continental EuropeCommon
IberiaOccasional

Common Occasional

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