Woodlice

Classification (systematic position) Source : INPN   Animal Kingdom Embranchement (Phylum) : Arthropoda Subphylum: Pancrustacea Class: Malacostraca Subclass: Eumalacostraca Order: Isopoda Under Order: Oniscidea

Morphological characteristics
Crustacean with an oval-shaped, flattened and segmented body, shell which may be transparent (exoskeleton composed of limestone, calcium phosphate and chitin), head (cephalon) with 2 pairs of antennae (one very small), thorax (pereon) with 7 segments all having a pair of legs (the woodlouse therefore has 7 pairs of legs), abdomen (pleon) composed of 5 tight segments on which are 5 pairs of pleopods (false legs present in certain crustaceans). Respiratory and reproductive organs are found in the pleon.

Life cycle
Woodlice breed in summer and the females carry the eggs in a ventral pouch under their thorax. The small woodlice are born in this pocket and develop there for about forty days then, once out, undergo moults for their growth until they have reached sexual maturity at one year. The woodlouse lives an average of 2 years and reproduces 1 to 6 times a year. Woodlice are active during the warmer months and their metabolism slows down during the winter.

Diet
Woodlice are detritivores, they feed on dead organic matter such as dead leaves and dead wood. Woodlice are able to digest cellulose thanks to a specific microflora present in their digestive tract.

Natural predators or regulators
Woodlice are predated by rodents, birds and spiders hunting on the soil surface. A species of spider Dysdera crocata feeds only on woodlice.

Habitats
Woodlice live in groups in dark places sheltered from light (heaps of wood, stones, leaves or in compost). They flee the light, they are lucifuges. Woodlice prefer calcareous environments (recovery of elements for their skeleton). In gardens, it is not uncommon to Porcellio scaber or Oniscus asellus.

Interests in the garden
Woodlice are harmless and actively promote the recycling of organic matter by accelerating the decomposition of the plants they fragment.

Did you know ?
It is easy to create a breeding of woodlice, by installing in a terrarium a thin layer of soil, a little tree bark and litter composed of leaves, to renew when everything has been devoured by the woodlice.

The species Oniscus asellus is used as a bioindicator in the study of soil pollution and in homeopathy. In the middle of the 18th century, the woodlouse was part of "the medicines in the king's hospitals". The external skeleton of woodlice indeed contains a lot of calcium carbonate which has the property of neutralizing stomach acids...