15 April: Woodlouse Appreciation Day

Today is Woodlouse Appreciation Day. Here are 10 facts about these humble garden creatures:

1. They’re not actually lice. Lice are insects while woodlice are land living crustaceans, more closely related to Shrimps or prawns than lice.

2. There are a ton of different woodlouse species. There are 40 species in 10 different families in Britain and something like 5,000 – 7,000 species worldwide. They can be found on every continent except Antarctica.

3. They have a shell-like exoskeleton, and moult as they grow. They have seven body segments, 7 pairs of legs and a pair of antenna to help them find their way around in the dark.

4. They live in moist environments. Like their aquatic ancestors, they breathe through gills located on their hind legs. Hence they must always have wet legs or they’ll suffocate. This is why they live under stones or old logs and are nocturnal, coming out at night when it’s cool. They have a strategy for conserving water if they find themselves in a dry environment. They conglobate. That is, they roll into a ball, rather like an armadillo does. In fact, there’s a species of woodlouse called Armadillidium vulgareare for this very reason. Conglobating is also a way to protect themselves against predators.

5. They’re technically marsupials. A female woodlouse keeps fertilised eggs in a marsupium, or pouch, on the underside of her body, formed by overlapping plates attached to the bases of the first five pairs of legs. The eggs hatch in there and the mother appears to “give birth” to fully formed young, although newly hatched woodlice only have six pairs of legs.

6. They don’t pee. Instead they get rid of waste in the form of a gas through their exoskeleton. Therefore they can smell nasty if kept in an enclosed space for too long. It’s also said that they taste like pee rather than like their cousins, Crabs, Lobsters or prawns. Frogs, centipedes, shrews, Mice and Spiders don’t seem bothered by the unpleasant taste and eat them anyway.

7. Woodlice are detritivores, which means they eat decaying matter and are thus a vital part of the ecosystem. They are generally thought to be beneficial to have in a garden as they help create compost and recycle waste.

8. If they get in the house, they won’t cause any harm as they don’t carry diseases or eat sound wooden structures. However, if you’ve got an infestation of them, it might mean there is damp somewhere.

9. They can be kept as pets in a moist terrarium. They’re easy to look after and will happily munch away on rotting vegetables. They’re also quite social creatures and will live together in groups of up to about 70 with no problems. Enthusiasts will selectively breed from them to encourage particular colours or patterns.

10. Because they’re so ubiquitous, there are any number of dialect words for these creatures, including potato bugs, wood pigs, fat pigs, chiggy pigs, roly polys, boat builders, doodle bugs, slaters, cheese logs and monkey peas. In Swedish it’s known as a grey sucker, in French, a close-door, and in Spanish, it’s named after a red insect from Mexico, traditionally used in dyes. In the Netherlands, they’re called pissabeds.