When does the Iron Blue hatch?

March–October, typically 13:00–16:00. It starts from about 7°C, peaks around 9°C and tails off by 14°C.

What flies imitate the Iron Blue?

Iron Blue Dun, Snipe & Purple, Waterhen Bloa, Large Dark Olive Dun, Pardón, typically on a #18–16 hook.

How big is the Iron Blue?

Spinner stage: 5–7mm. That matches a #18–16 hook.

Mayfly · Aquatic insect

Iron Blue

Baetis niger

Size

5–7mm

Hook size

#18–16

Hatch window

Season March–OctoberPeak time 13:00–16:00

Water temperature

9° peak

7°14°

How fish feed on it

Small, dark and easy to miss against broken water. Worth having when a good iron blue hatch tails off and the fish keep rising to something you cannot see.

Flies that imitate this

Iron Blue Dun

Snipe & Purple

Waterhen Bloa

Large Dark Olive Dun

Pardón

Ecology

Rivers & stillwaterAlpine rivers

Where you'll find this

British IslesPresent
IberiaPresent
The AlpsPresent
ScandinaviaPresent
Continental EuropePresent
Atlantic fringePresent

Present throughout

About the genus Baetis

Baetis is a genus of mayflies of the family Baetidae, known as the blue-winged olive to anglers. There are at least 150 described species in Baetis . They are distributed worldwide, with the most variety in North America and northern Europe.

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