What are woodlice?

Woodlice are terrestrial crustaceans belonging to the order Isopoda. They shelter in dark damp places, especially where there are accumulations of decaying plant material. They feed on this material and are an important part of nutrient recycling in the garden. 

Symptoms

Woodlice feed largely on damp decomposing plant material and are therefore useful recyclers in the garden. 

Woodlice do not usually damage healthy plants, they can however become associated with damage which has other causes such as slug damage or plants that have died and begun  to rot. Woodlice occasionally damage very soft plant tissues, such as seedlings and sometimes strawberry fruits.

Holes in older, tougher plant material will have been caused by something else, such as slugs or caterpillars.

Control

• Woodlice are not usually plant pests and are useful recyclers of decomposing vegetable matter
• They are naturally abundant in a healthy garden
• Control is not usually necessary
• Woodlice can come into houses from gardens but are unlikely to survive for long indoors unless they can find a damp place to shelter
• Woodlice are food for many other creatures such as shrews, toads, centipedes, some spiders, ground beetles and parasitic flies

Biology

During the day, woodlice hide in dark damp places so they are often found under logs, stones and flower pots. At night they move around in search of food, which is mainly rotting plant material.

There are several species of woodlice commonly found in gardens. They are up to 1cm (½in) long and are often grey in colour, with the body segments sometimes flecked with yellow or pinkish brown markings. Some species, known as pillbugs, can roll themselves into a ball when threatened.

Woodlice produce eggs in spring and these are retained inside the female’s body until they hatch. The newly hatched woodlice, known as mancas, are kept in a brood pouch on the underside of the female for a few days before they disperse.

Immature woodlice are similar in appearance to the adults and they shed their outer shells on a number of occasions as they grow bigger. They become adults by late summer and overwinter before reproducing in their second year.

More information on woodlice can eb found from the British Myriapod and Isopod Group