If there is a high level of humidity in your house then one of your residents must be the tank- like packed creature commonly known as the woodlouse. Woodlice are terrestrial cousins of the familiar coastal and marine crustaceans, such as crabs, lobsters, crayfish, shrimp, krill and barnacles. The latter hosts 50,000 described species till now and Woodlice are just one suborder of a group called Oniscidea, within the order Isopoda, with over 3,000 world-wide known species. Generally, woodlice are identified by their rigid, segmented, long exoskeletal and fourteen jointed limb body. The number of local species is still uncertain, but the level of interest is high as some species like Maltese Woodlouse, Armadillidium schmalfussi, Ħanzir l-Art ta’ Malta and the Maltese Cave Dwelling Woodlouse, Armadillidium aelleni, Ħanzir l-Art tal-Gћerien ta` Malta are endemic to our archipelago and the latter, as name implies, is confined to caves.

Woodlice need moisture because they breathe through gill like structures called pseudo-trachea, and thus are usually found in damp, dark places, such as under rocks, wood or in our basements. They are usually nocturnal (night dwellers) and are detritivores, i.e. they feed mostly on dead plant matter, though they have been known to feed on cultivated plants, such as ripening strawberries and tender seedlings. Woodlice are ecologically very important because their mode of feeding ultimately leads to a faster replenishment of nutrients back to the soil. In artificial environments such as greenhouses, where they can be very moist, woodlice may become abundant and damage young plants.

Besides the Common Maltese Woodlouse, which one may occasionally find in a residence, the Common Woodlouse, Armadillidium vulgare, Ħanzir l-Art Komuni, is the most familiar one in establishments and unfortunately the one which is regarded the most as a pest. These creatures are harmless and also beneficial, but seen as pests because they tend to congregate in large numbers. On some house facades each year, thousands cover the facades during the evening and then disperse or die out in the morning. This behaviour is still a phenomenon not understood. This species may reach a length of 18 mm, and is capable of rolling into a ball when disturbed. This ability, along with its general appearance, gives it the name pill-bug and also creates confusion with pill millipede species.