Common Pygmy Woodlouse - Trichoniscus pusillus agg.

Alternative names
Pygmy Woodlouse

This small red woodlouse (up to 5 mm) is sometimes called the Common Pygmy Woodlouse. This is a small purplish-reddish species with eyes composed of three ommatidia and a smooth body surface. Recently, studies have shown that there are in fact two very closely related species which can only be separated by looking at differences in genitalia, hence the term 'agg.' to describe the species pair. The females are visually indistinguishable.

Identification difficulty

Gardens under stones and logs or in damp soil and leaf litter in woodland.

When to see it

All year round.

Life History

This species is capable of reproducing by parthenogenesis, whereby the female gives birth to clone offspring without male fertilisation.

UK Status

It is widespread and one of the most common woodlice in Britain.

VC55 Status

Very common in Leicestershire and Rutland.

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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