When does the Ephemera orientalis hatch?

May–September, typically 17:00–20:00. It starts from about 13°C, peaks around 19°C and tails off by 26°C.

What flies imitate the Ephemera orientalis?

Sakasa Kebari, CDC Olive Emerger, Comparadun, typically on a #14–12 hook.

How big is the Ephemera orientalis?

Spinner stage: 13–17mm. That matches a #14–12 hook.

Mayfly · Aquatic insect

Ephemera orientalis (Lowland Mayfly)

Ephemera orientalis

Size

13–17mm

Hook size

#14–12

Hatch window

Season May–SeptemberPeak time 17:00–20:00

Water temperature

19° peak

13°26°

How fish feed on it

By the time the spinners are down the fly has finished its job and is simply lying there, spent, wings flat in the film, going nowhere. Trout know the difference between something alive and something that's stopped trying, and they take spinners with a quiet, unbothered sip that's easy to miss if you're still watching for something splashier. Look for them on the glides and in the slack water, wherever the current gathers what's left.

Flies that imitate this

Sakasa Kebari

CDC Olive Emerger

Comparadun

Ecology

Rivers & stillwaterLowland rivers

Where you'll find this

East AsiaPresent

Present throughout

Identification

Ephemera is a genus of mayfly in family Ephemeridae. It contains the following species:

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