Southern Iron Blue Mayfly - Baetis niger


A brown bodied mayfly with bluish slate grey wings.


Nymphs are found in running waters throughout the British Isles with the exception of Ireland, they typically crawl amongst in-stream vegetation in riffle areas of rivers and streams or swim in short, darting bursts amongst the substrate.

When to see it

There are two generations per year - a slow growing winter generation and a much faster summer generation.ÿ This results in a fairly long flight period, with adults being present between April and October.ÿ

Life History

Larvae feed by scraping algae from submerged stones and other structures, or by gathering or collecting fine particulate organic detritus from the sediment.ÿThe males of this species can be found swarming throughout the day and often swarming continues until dusk.

UK Status

A widespread, but localised species in Britain.

VC55 Status

Status in Leicestershire and Rutland not known.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map