Pill bugs, known for their ability to curl into a tight sphere, are commonly called roly-polies, woodlice, or potato bugs. These small, segmented creatures are not insects but terrestrial crustaceans, related to shrimp and lobsters. Sporting a hard, armor-like exoskeleton of seven overlapping plates, they typically appear gray or brown. Pill bugs play a beneficial role in ecosystems as decomposers, breaking down decaying organic matter and returning nutrients to the soil.
Essential Needs: Moisture, Shelter, and Food
Pill bugs are primarily attracted to environments that satisfy their fundamental needs for moisture, shelter, and food.
Pill bugs require damp conditions due to their gill-like respiratory system. These organs need moisture to function, preventing desiccation. This explains their presence in high-humidity areas like damp soil or decaying wood.
Beyond moisture, pill bugs seek dark, confined spaces for protection from predators and harsh conditions. Their ability to roll into a ball (conglobation) aids self-preservation and reduces water loss. These sheltered spots provide a stable microclimate, shielding them from extreme temperatures and dry air. Their nocturnal activity is guided by these preferences, as they are most active during cooler, damper hours.
Their diet primarily consists of decaying organic matter, classifying them as detritivores. They consume decomposing plant materials like fallen leaves, rotting wood, and garden mulch. This feeding habit breaks down organic waste, enriching the soil by cycling nutrients. While their main food source is dead vegetation, they may occasionally consume fungi, algae, or animal matter.
Where You’ll Find Them
Given their specific environmental requirements, pill bugs are frequently found in particular locations, both outdoors and indoors.
Outdoors, they thrive in gardens, compost piles, and areas with abundant moisture and decaying organic material. Common habitats include beneath rocks, logs, stepping stones, and leaf litter, providing dampness and shelter. They are also found under potted plants and within thick mulch layers, accessing preferred food sources.
Indoors, their presence is typically accidental, as they enter structures seeking moisture. Basements, crawl spaces, and bathrooms are common indoor locations prone to dampness. They gain entry through ground-level openings like foundation cracks, door gaps, or ill-fitting window screens. However, the dry indoor environment means they cannot survive more than a few days without consistent moisture.
Are They a Problem?
Pill bugs are generally considered harmless and beneficial organisms in garden ecosystems. They do not bite or sting humans and are not known to transmit diseases. Their role as decomposers is valuable, contributing to soil health by breaking down organic matter and returning nutrients. Many gardeners appreciate their presence in compost piles, where they accelerate the decomposition process.
While their primary diet is decaying material, large populations can occasionally cause damage to living plants, particularly young seedlings, tender shoots, or soft fruits that are in contact with the ground. This damage is more likely to occur when other food sources are scarce or during periods of excessive moisture that lead to population booms. However, such instances are relatively uncommon, and their presence usually suggests an underlying moisture issue in the area rather than a pest infestation.