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OK, so I maybe I was a bit of a weird kid - never played much with dolls or tea-sets or any of the other so-called 'girly' pursuits. Instead I would forage around in the garden for hours, and bring my new friends - woodlice - in for tea (not to eat I hasten to add, although recipe follows). I didn't know much about them then, apart from the fact that they were good fun to play with, but although I'm now well and truly a 'grown-up' I still find them interesting.

Some facts about the common woodlouse (UK).

I'm pretty sure that everyone knows what common woodlice look like, but for completeness I will describe them here.

  • They are usually grey/brown or reddish in colour, have oval segmented bodies (up to about 1 cm in length). If you look carefully you can see that the body is divided into 3 regions, the head, thorax and pleon (abdomen). They have 7 pairs of legs, 1 pair of compound eyes, antennae (2 pairs, but only 1 pair noticeable), may or may not have 2 tails depending on the species. Woodlice have blue blood - oxygen is carried around their bodies by haemocyanin, a copper based molecule (hence the blue colour) similar to haemoglobin, but the quantities are so small that the colouration is not noticeable.


  • Woodlice are not insects; they are related to crabs, shrimps and lobsters, and they belong to a small group of Crustaceans that can survive on land. There are some 3500 species of woodlice worldwide. Approximately 10% of these are native to the UK, the three most familiar ones being Oniscus asellus and Porcellio scaber (Common shiny woodlouse and Common rough woodlouse) and Armadillidium vulgare (Common pill bug, has interlocking plates like an armadillo). The earliest fossil records date from around 50 million years ago but they probably evolved earlier than that.


  • Woodlice may be known under a variety of folk names including: Coffin-cutters, Pillbug, Roly Poly, Monkey peas, Penny pigs, Sink-lice, Slaters, Sowbugs and Tiggyhogs. The name pill bug comes from its ability to roll up into a tight ball resembling a pill - in fact they used to be prescribed as a medicine for indigestion (maybe the high calcium content of the shells helped a little?). Farmers would give them to cows to improve their cud, hence the term cud-worm.


  • Woodlice live in dark, damp areas with lots of vegetation; they actively avoid light and tend to huddle together in groups when not active as a way to preserve moisture, prevent desiccation and also for protection against predators. They have gill-like structures on their underbellies which need to remain moist in order to absorb oxygen from the air; if these dry out the woodlouse dies, conversely if it gets too wet the woodlouse drowns.


  • Woodlice feed at night, they are mostly vegetarian, occasionally cannibalistic and always coprophagic (there're lots of nutrients in woodlouse poo!). They do not eat carpets, furniture etc. and are not, therefore, pests in the home.


Life cycle

Woodlice mate under cover of darkness in the summer months. The male finds a receptive female, climbs on her back and licks her head while stroking her back with his front legs. The female has 2 genital openings, 1 on either side of her body and the male deposits sperm first into one, and then the other, the whole procedure taking about 5 minutes on each side. The female produces up to around 200 eggs, depending on her age and size and most species only have one brood a year. When she is ready to mate she lays her eggs in a marsupium - a special brood chamber grown from plates under her body, where the babies are kept moist and protected against predators. The newly hatched babies are light in colour and have only 6 pairs of legs; they remain in the marsupium until their first moult, after which the 7th pair of legs emerges and they leave their mother.

As with all other arthopods, woodlice need to moult in order to grow. They are somewhat unusual in that they moult in 2 phases - first the back half of the shell comes away, then a few days later the front half is replaced. They are very vulnerable at this time because the new shell takes time to harden - this is the time when they might even be eaten by their own kind.

Woodlice as food.

Woodlice are eaten by a range of animals, the most numerous being shrews, toads, ground beetles, centipedes and some spiders. Humans may also find them appetising! According to Vincent M Holt, in his book "Why Not Eat Insects", woodlice have a superior flavour to prawns being both fishy and crunchy. (yuck!)

To ensure a clean woodlouse it is recommended that they are raised on kitchen paper for a few days and fed potato. They produce a repellent fluid which is removed by initially boiling the creatures for a couple of minutes before preparing the recipe; obviously this also has the effect of killing the woodlouse at the same time.


Woodlouse fritters.

  • 1 egg
  • 1/4 cup of creamed corn
  • 1 cup flour
  • 2 table spoons killed woodlice
Put egg in a bowl, add corn, flour, woodlice and milk. Lightly mix. Ingredients should be moist - add more flour or milk as required to make mixture the correct consistency.
Drop spoonfuls of the mixture into a thin layer of hot oil in a frying pan. Turn when brown on the bottom.

Tastes like whitebait patties - allegedly!

http://www.geocities.com/~gregmck/woodlice/recipes.htm for more recipes!

Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Isopoda
Suborder: Oniscidea

'Woodlouse' is the common name for creatures of the suborder Oniscidea. Oniscidea includes all of the isopods that have adapted to life on land. Most of us know them as small grey 'bugs' that live in rotting leaves and roll into a ball when you try to pick them up; these are woodlice of the genus Armadillidium, and are called by a variety of common names, such as pill bug, sowbug, roly poly, or simply woodlouse. While for the most part all woodlice look similar to the familiar pill bug, most cannot roll into a ball, and some have distinguishing features such as large splayed-out legs or interesting coloration (bright red or ghostly white). All woodlice, however, share a common core of features; many of the most obvious features, in fact, are shared not only by all woodlice, but also by all isopods. So let's start with some general information on isopods.

Isopods all have 14 legs, two sets of antenna, and a segmented exoskeleton. Behind the seven sets of legs there are a set of unassuming appendages that are used for locomotion in in the marine isopods, and for respiration in all isopods. Most isopods are quite small, but the aptly named giant isopod grows about as large as a horseshoe crab, looking like a giant trilobite, or for that matter, a giant woodlouse.

Woodlice are surprisingly like their marine cousins, having made only the minimal adjustments required for living on land. However, small as the changes may be, they are commonly underemphasized. For example, the common belief that woodlice have gills is incorrect; woodlice took the gill-like structures on their pleopods and added a set of rudimentary air sacs, resulting a structure known as a pseudotrachea. This structure works best when damp, so woodlice lurk in piles of rotting leaves and other protected lairs, preferring to come out only at night. But if need be, a woodlouse can leave these areas and travel through the world at large, including scorchingly dry environments.

Many species of marine isopods carry their young in fluid-filled brood sacs, from which the young do not emerge until they are nearly fully-formed miniature replicas of the adults (called manca). This is a very useful pre-adaptation to terrestrial life, and the woodlouse has continued this tradition of ovoviviparity. In woodlice the newly emerged young, although equipped with only six sets of legs rather than the full seven, are mobile enough to seek protection and dampness. If you ever get the chance to breed woodlice, watch for the sudden explosion of tiny little woodlicettes.

Speaking of breeding woodlice -- one of the adaptations that most animals make when moving onto land is to stop excreting the nitrogen waste resulting from protein metabolism as ammonia and dispose of it as urea or uric acid instead. This allows them to store the toxic ammonia within their bodies and conserve water. Woodlice went in a different direction. Woodlice dispose of ammonia by emitting it as gas, with the undeniable result that they stink.

Woodlice are almost always scavengers, eating rotting plant material or, in some cases, spoiled meat. This is largely because isopods need copper to build the hemocyanin in their blood (the equivalent to our hemoglobin), and the copper found in living plants is bound too tightly in stable organic compounds. Once the plants start to decompose the copper becomes more accessible, and the woodlice can digest it. If sufficient levels of rotting vegetable matter are not present, woodlice can also replenish their copper stores by eating their own feces. In order to avoid this eventuality, woodlice have evolved to store more copper in their bodies than can aquatic isopods (who generally absorb sufficient copper from the surrounding water).

There are between 4,000 and 5,000 known species of woodlice, so any description has to be general in nature. However, it is worth noting that there are species of woodlice that eat rotting meat, species that live in burrows in the hottest of deserts, species that live in a symbiotic relationship with ants (Platyarthrus hoffmannseggi, the Ant Woodlouse), and in hypersaline pools. Woodlice are the most populous and most widespread of terrestrial crustaceans.

When researching this writeup, I found many references to 'the common woodlouse'. As you might expect, the 'common' woodlouse is different depending on where you live. With approximately forty different families and thousands of species, the term 'common woodlouse' is essentially meaningless unless the writer specifies where exactly the woodlouse is common to. However, two of the most common woodlice are Oniscus asellus, the Shiny Woodlouse and Armadillidium vulgare, the Common Pillbug.

Recommended reading for practical woodlouse hunting.

While an truly unwieldy number of sources were used in composing this writeup, it would not be half as good as it is without the help of the book The Colonisation of Land: origins and adaptations of terrestrial animals By Colin Little.

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