February Bug of the Month: Woodlice

Woodlice are one of Britain’s most common and easily recognised invertebrates, and at any time of the year, they can be found sheltering during the day under plant pots, logs and amongst loose brickwork where they can live for up to three years. 

Despite having more than 30 species that reside in Britain, they all look very similar, with jointed antennae and an oval-shaped, plated exoskeleton that resembles a medieval suit of armour. However, whilst the majority of species are grey, some will appear brown or even a shade of pink.

Whilst others will also have the ability to roll into a ball when disturbed, which has resulted in them acquiring the common name of Pill Bug or Rollie Poly. Mistakenly, woodlice are sometimes referred to as insects. However, they're crustaceans, related to crabs and shrimps, and belong to the suborder Oniscidea within the order Isopoda.

Just like the aquatic species, terrestrial woodlice breathe through gills which are located on the underside of their abdomens; these gills are very delicate organs that need to be kept moist and so hence the reason why woodlice are primarily nocturnal and remain at rest in the dark damp locations during the day, often in large groups. It’s within these damp locations that the woodlice breed, and where the females tend to their eggs and hatchlings within a pouch on the underside of their bodies for up to two months.

In most gardens, the woodlice will be doing a lot more good than harm, feeding on detritus, particularly the more woody material, and recycling nutrients into the soil through their faeces.

Woodlice also provide a valuable food source for other wildlife that predate on them such as amphibians, birds and spiders. Where woodlice have become a problem, the simple and environmentally safe alternative to using a proprietary woodlouse-killing pesticide, which may then harm other beneficial creatures, is to sweep them up in a dustpan and release them under a hedge or in the compost bin.