Friday 28 December 2012

Woodlice Parade

Woodlice are the easiest crustacean group to spot in the garden. Sure, your garden pond will likely contain several aquatic crustacean groups: Water Fleas, Copepods and Ostracods are likely. Woodlice are amongst the few crustacean groups that are truly terrestrial - although aquatic forms both freshwater and marine are also found.
Despite their terrestrial habits, woodlice species differ in how much humidity they need to survive. Some can live in very dry habitats, while others need a constantly high level of dampness.
 There are over 45 British species of woodlice, of them I have found six locally. Here I have put together a parade which might help you identify your garden woodlice.

1. Common Pill Woodlouse, Armadillidium vulgare. Pill woodlouse are quite resistant to low humidity conditions and live in dry, sandy habitats. When disturbed they roll into a ball, protecting their legs and antennae.

2. Rough Woodlouse, Porcellio scaber. Another species that can live in relatively dry habitats, like under pots. Recognised by its matt, bumpy grey surface. They tend to grip the ground with their legs when disturbed, making it difficult to dislodge them as their flared segments form a continuous surface with the ground, and then they can walk more or less fast. Very common and often found in large aggregations in suitable habitats (top shot).

3. Smooth Woodlouse, Oniscus asellus. A large, flattened woodlice with a shiny surface. As the rough woodlice, it tends to freeze and sit tight, making it hard for predators to dislodge it from the ground, although it can also move away. It is one of the largest woodlouse species in the UK.

4. Common Striped Woodlouse, Philoscia muscorum. Amongst leaf litter. A fast woodlouse, which rapidly hides when disturbed. Beautifully patterned, shiny with a dark head.

5. Rosy Woodlouse, Androniscus dentiger. A small species which favours damp habitats with rotting wood or organic material. Pinkish with a yellow dorsal stripe and dark contrasting eyes. It is the rarest in my garden.

6. Water Slater, Asellus aquaticus. Found in the leaf litter at the bottom of ponds. Long antennae, although many lost due to fights, then they regenerate (see photo below). Males larger than females.

More information
A key to British woodlice by Jon Rosewell, in the iSpot resources.
Walking with Woodlice, a Natural History Museum project.
Browse BugBlog's woodlouse related posts.


Lucy Corrander Now in Halifax! said...

Very beautiful pictures. Until I read this I had thought all woodlice curl into a ball. Shows how we extrapolate from our childhood experiences. The curl-up kind were very common in our garden then - though it's the Rough Woodlice I most notice where I live now.

Sara Rall said...

Just found your blog and I love your guide to woodlice. I've gotten to the point of telling at least four types apart in my yard, but haven't got names for them yet. Your pictures are quite helpful.

Africa Gomez said...

Thank you for your comments Lucy and Sara, I am glad the post was useful.

conall said...

This is terrific -a really enjoyable read and great pictures too- i have been meaning to read something on woodlice for a while - great to find this - really accessable start. We dont seem to have any of the pill type ones (i love that genus name Armadillidium!) here in my area of county down - I think our common big one here must be Porcellio scaber. I am going to do a bit of turning over stones and branches next weekend - looking forward to it already!

Africa Gomez said...

Thank you for your lovely comment conall, and good luck with your woodlice hunting!

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