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Woodlouse

Woodlice are terrestrial isopod crustaceans in the suborder Oniscidea.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 27, 2026|2 min read| Fact-checked

Woodlice are terrestrial isopod crustaceans in the suborder Oniscidea. They are not insects and are more closely related to crabs and shrimps; many species live in damp places and feed on decaying plant matter.

Classification

Woodlice are terrestrial isopod crustaceans placed in the suborder Oniscidea. They are part of the order Isopoda and class Malacostraca, and are unrelated to insects despite their name.

Description and adaptations

Woodlice have a segmented exoskeleton and many species have a flattened body shape. Their land lifestyle depends on moisture, so they are commonly found in damp, shaded places where they avoid drying out.

Habitat and behaviour

Woodlice occur in habitats such as leaf litter, rotting wood, rocks, compost heaps, and garden shelters. Some species can roll into a ball for protection, while others remain flattened and rely on hiding places.

Ecological role

Woodlice feed largely on dead plant material and other decaying matter. This makes them important decomposers that help recycle nutrients back into the soil.

Key facts

  • Woodlice are crustaceans, not insects.
  • They belong to the suborder Oniscidea within the order Isopoda.
  • They are adapted to land but still need moist conditions.
  • Many species live under stones, logs, bark, or in compost heaps.
  • Some species can roll into a ball when disturbed.
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Canadian context

Woodlice are common in gardens, compost, and damp outdoor habitats in Canada, where they play a useful decomposer role.

Frequently asked questions

Are woodlice insects?
No. Woodlice are crustaceans in the suborder Oniscidea, not insects.
Where do woodlice live?
They usually live in damp, dark places such as under stones, logs, bark, and in compost heaps.
What do woodlice eat?
They mainly eat dead plant matter and other decaying organic material.
Can woodlice roll into a ball?
Some species can curl into a ball as a defence mechanism, which helps protect their softer underside.
Why are woodlice important?
They break down decaying material and help recycle nutrients in soil.

References

  1. Encyclopaedia Britannicahttps://www.britannica.com/animal/wood-louse
    Supports: Woodlice as terrestrial crustaceans; relationship to pill bugs and sow bugs.
  2. Wikipediahttps://en.wikipedia.org/wiki/Woodlouse
    Supports: Definition of woodlice as terrestrial isopods in Oniscidea; distinction from insects.
  3. Merriam-Websterhttps://www.merriam-webster.com/dictionary/wood%20louse
    Supports: Dictionary definition; terrestrial isopod crustacean and ball-rolling trait.
  4. The Wildlife Trustshttps://www.wildlifetrusts.org/wildlife-explorer/invertebrates/crustacea-centipedes-and-millipedes/common-woodlouse
    Supports: Habitat, diet, and ecological role in recycling nutrients.
  5. London Borough of Waltham Foresthttps://www.walthamforest.gov.uk/sites/default/files/2021-10/Woodlice%20fact%20sheet.pdf
    Supports: Species counts, habitat, body features, and ball-rolling pill woodlouse note.