The woodlouse, often encountered in damp corners of gardens or under logs, is a common terrestrial creature that many people might mistake for an insect. However, these organisms are not insects at all; they are crustaceans, more closely related to crabs and lobsters. They represent a unique adaptation of marine life to a terrestrial environment, thriving in places where moisture is abundant.
Identifying a Woodlouse
A woodlouse has a segmented, oval-shaped body and a hard, shell-like exoskeleton. This exoskeleton, often grey, brown, or black, is divided into seven plates, with each segment of its thorax bearing a pair of legs. Unlike insects, which typically have three pairs of legs, woodlice have seven pairs. They also have two pairs of antennae, though one pair is usually much shorter and less visible.
Many common names are used for woodlice, such as “roly-poly” or “pill bug,” which stem from a unique defensive behavior exhibited by some species. When threatened, certain woodlouse species, particularly those in the family Armadillidiidae, can roll themselves into a tight, spherical ball, protecting their softer underside. This ability to conglobate is a key difference between “pill bugs” and “sow bugs”; while pill bugs can roll completely into a ball, sow bugs (which often have two tail-like appendages) cannot and tend to scurry away when disturbed.
Where Woodlice Thrive and What They Consume
Woodlice require damp, dark environments to survive. Despite living on land, woodlice breathe using gill-like structures, which must remain moist to facilitate gas exchange. Without sufficient moisture, they risk suffocating. They are found under rocks, logs, leaf litter, and in other sheltered, humid locations like basements, compost piles, or even decaying wood structures. They are primarily nocturnal, active at night to avoid desiccation.
As detritivores, woodlice primarily feed on decaying organic matter. Their diet typically includes dead leaves, rotting wood, fungi, and other decomposing plant debris. They also consume mold and sometimes even their own feces, which aids in nutrient absorption. Occasionally, they might consume soft, decaying fruits or vegetables. This dietary preference highlights their role in the natural recycling process, as they break down organic materials that other organisms might not consume.
The Woodlouse’s Environmental Contribution
Woodlice are important decomposers within various ecosystems. By breaking down dead plant material, they facilitate the return of essential nutrients to the soil, contributing to soil health and fertility. This process, known as nutrient cycling, is fundamental for natural environments. Their activity also helps to improve soil structure and aeration, benefiting plant roots and other soil organisms.
Woodlice are generally considered beneficial and are not typically pests. They rarely cause damage to healthy, living plants, preferring to feed on material that is already dead or decaying. If woodlice are found indoors, it usually indicates a moisture problem, such as a leaky pipe or damp basement, rather than an infestation causing structural damage. Their presence can even serve as an indicator of a healthy environment, as they are part of a complex food web, serving as a food source for various predators like spiders, birds, and small mammals. They can also accumulate heavy metals from the soil, assisting in environmental cleanup.