Scientific name: Porcellio scaber
Woodlice are in the Order Isopoda and there are about 35 species in the British Isles. They are Crustaceans related to crabs and lobsters, indeed if cooked they make a passing alternative to prawns on the flavour stakes (so I'm told!). In a damp corner where they have been around for a while there can be slight 'fishy' smell.
A calcareous shell made up of segments covers their body. They are liable to water loss so require damp conditions. Constantly running the risk of dehydration, they need a moist atmosphere to breath, but are also able to absorb moisture from the atmosphere. In dry conditions they shrivel up, becoming dried out corpses when they venture into the modern heated home.
They reproduce by giving birth to live young. The female develops plates at the base of the front five pairs of legs which meet together under the thorax to form a water-filled cavity. The embryos develop there and after several weeks immature young emerge before moulting. As the woodlouse grows it sheds its exoskeleton in two halves which split across the centre and the front separates from the back.
Like millipedes, they are detritovores feeding mainly on plant debris, although seedlings are sometimes attacked. Their ability to break down larger particles of organic material makes them an important part of the rotting process.
In the commercial glasshouse they will damage the stems and lower leaves of cucumbers, but are only a problem in the domestic setting around young seedlings. Rotting timber and brickwork provide a suitable hiding place, so removing these from near vulnerable plants is helpful.
Removing plant debris to discourage them is all that is required in most gardens. In the commercial setting they can be controlled by soil sterilization with steam or methyl bromide .
Diatomaceous Earth is a mined product and consists of tiny fossilized diatom remains. It works by sticking to the exoskeleton of the woodlouse by static attraction and abrades it as it moves around resulting in holes which lead to dehydration and death. It is applied as a fine powder to paths and areas where crawling invertebrates are present.
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