Woodlice, often known as roly-polies, pill bugs, or sow bugs, are terrestrial crustaceans frequently found in gardens and homes. A common misconception suggests that woodlice consume sound wood, potentially causing structural damage. However, understanding their true nature and feeding preferences clarifies their actual role and interaction with wooden materials.
What Woodlice Actually Eat
Woodlice are detritivores; their primary diet consists of decaying organic matter. They play an important role in breaking down dead plant material, contributing to nutrient recycling in soil. Their typical food sources include rotting leaves, bark, and wood that has already begun to decompose. Fungi and molds also form a significant part of their diet. They may also consume decaying vegetables, soft fruits, and occasionally dead insects or animal droppings.
The woodlouse digestive system is adapted to process this soft, decaying material. Unlike pests that bore into healthy timber, woodlice lack the mouthparts and enzymes to break down intact, sound wood. While they might occasionally nibble on tender seedlings or damaged plant roots if preferred food sources are scarce, this is not their usual feeding behavior. They pose no direct threat to solid, dry wooden structures.
Why Woodlice are Drawn to Wood
Despite not consuming healthy wood, woodlice are frequently found in and around wooden environments. Their attraction stems from specific environmental requirements, particularly their need for moisture. As crustaceans, woodlice rapidly lose water, making damp, humid conditions essential for survival. They seek dark, sheltered places offering protection and stable moisture.
Outdoors, wooden areas like rotting logs, leaf litter, or under stones provide ideal habitats. These locations accumulate decaying organic matter, fungi, and mold—their actual food sources. Indoors, woodlice are drawn to damp areas like basements, crawl spaces, or near plumbing fixtures, where moisture is prevalent and decaying materials may be present. Their presence inside a home indicates an underlying moisture issue, not an intent to consume the structure.
Woodlice and Structural Damage
Woodlice do not directly damage sound, dry wooden structures. Their mouthparts are designed for scraping and chewing soft, decaying matter, not for boring into solid timber. A healthy, well-maintained wooden beam or floorboard is not at risk from woodlouse activity. If woodlice are found near wooden elements in a home, it signals an existing problem, such as dampness or pre-existing rot.
While they do not eat healthy wood, woodlice may feed on wood already decaying due to moisture or fungal growth. They might cause superficial damage to very soft, damp wooden surfaces, furniture, or wallpaper if mold is present. This is distinct from the extensive, destructive damage caused by true wood-boring pests like termites, which consume sound wood, or carpenter ants, which excavate tunnels for nesting. The presence of woodlice primarily indicates excess moisture, which can attract other, more destructive pests.