Bug Wiki
Sticker of Swift woodlouse
Bug card No. 1320 of 1,500

Swift woodlouse

Porcellio laevis
Eats: Leftovers and dead thingsWoodliceGardens and meadows14 legsNot an insect, but a bug cousin

The swift woodlouse is a big woodlouse with a smooth, shiny back. As its name says, it can run off really fast when something bothers it. It is one of the biggest woodlice, up to 2 centimetres long.

Fun fact: woodlice are not insects. They are crustaceans, cousins of crabs and shrimps, that live on land.
Lives in
Almost all over the world, under rocks and logs, in compost and dung heaps
Length
2 cm (0.79 in)
Top speed
about 0.19 km/h (0.12 mph)
On foot, estimate
Can it hurt you?
Harmless
Harmless. It cannot bite or sting, and it is fine to watch it up close.
What does it eat?
It eats dead leaves, moss, lichens, rotting wood and animal droppings, and turns them back into good soil.
For real!Photo of Swift woodlouse
Picture by Pudding4brains. Public domain, via Wikimedia Commons.

How big is it?

How long is it?

Swift woodlouse about 2 cm long (0.79 in)A grain of rice about 6 mm (0.24 in)A toy building brick about 3.2 cm (1.3 in)A crayon about 9 cm (3.5 in)
as long as 3 grains of rice in a rowit has about 14 legscould run across a dinner table in 19 seconds

How big is Swift woodlouse compared to YOU?

Just maths in your browser. Nothing is saved or sent anywhere.

How fast is it?

cool stuff

Fun facts

1

The mother carries her eggs and babies in a pouch full of liquid under her body, a bit like a kangaroo.

2

To escape, it runs in zigzags, left, right, left, to confuse whoever is chasing it.

3

People keep it as a pet in terrariums, and there are many colour types.

4

It probably first came from North Africa, but it was already in Britain about 800 years ago.

5

Birds, lizards and small mammals love to eat it.

you asked

Most asked questions about Swift woodlouse

?Are woodlice insects?

No. Woodlice are crustaceans, related to crabs and shrimps. They have 14 legs, not 6.

?What does the swift woodlouse eat?

Dead plants, rotting wood, moss and droppings.

?Can you keep a swift woodlouse as a pet?

Yes. It is easy to keep in a damp terrarium with leaves and bark.

For bug experts

Scientific name
Porcellio laevis
Group
Woodlice
Family
Porcellionidae
Classification
Malacostraca > Isopoda > Porcellionidae
Lives on
Africa, Europe, Asia, North America, South America, Australia and Oceania
Also known as
Smooth slater

Where the facts come from

  1. Porcellio laevis (Wikipedia, CC BY-SA 4.0): what it looks like, where it lives, what it eats, sizes and fun facts, retold in simple words.
  2. Picture by Pudding4brains. Public domain, Wikimedia Commons. The round sticker of this bug is cut from the same picture.

If we got something wrong, sorry, we are bug fans, not a science journal. Tell us at [email protected] and we will fix it.

More from the same group: Woodlice

Also at home here: Gardens and meadows