Pill bugs, commonly known as roly-polies or woodlice, are small, shelled creatures often found in gardens and damp environments. These organisms are not insects, but terrestrial crustaceans, more closely related to shrimp and crabs. Understanding what attracts them helps explain their presence and how they can be managed in human spaces.
Understanding Pill Bugs
Pill bugs are land-dwelling crustaceans belonging to the order Isopoda. The most common species, Armadillidium vulgare, is found globally. They have oval, segmented bodies, typically 1/4 to 3/4 inches long. Their hard, shell-like covering of overlapping plates allows them to curl into a tight ball when disturbed, a defense mechanism that gives them their common name. They possess seven pairs of legs and two pairs of antennae.
Pill bugs are decomposers, primarily consuming decaying plant material. This activity recycles nutrients back into the soil, improving its quality and supporting plant growth. They also burrow through soil, aiding in microorganism redistribution and releasing nutrients.
Environmental Conditions They Seek
Pill bugs are attracted to moisture, darkness, and shelter. They breathe through gill-like structures, requiring a consistently moist environment to prevent desiccation. Without adequate humidity, pill bugs can only survive for about two days indoors. This need for moisture often makes them nocturnal, seeking damp spaces during the day to avoid dehydration.
They commonly inhabit areas with high humidity and shade, such as under rocks, logs, leaf litter, and mulch. These locations provide both moisture and protection from direct sunlight and predators. Basements, crawl spaces, and areas near building foundations that retain moisture also attract pill bugs. They often bury themselves several inches below ground to escape heat and dry air.
What They Consume
Pill bugs are primarily detritivores, meaning their diet consists mainly of dead and decaying organic matter. They are attracted to a variety of decomposing plant materials, including fallen leaves, rotting wood, fungi, and other plant debris. Their feeding habits contribute to nutrient cycling, as they break down organic matter and return valuable nutrients to the soil. This process enhances soil fertility, making them beneficial in many natural settings.
While their primary diet is decaying matter, pill bugs may occasionally consume tender live plants, especially when other food sources are scarce. This can include young seedlings, new roots, and fruits or vegetables that are in contact with damp soil. In agricultural settings, particularly during wet conditions or when large populations are present, they have been observed feeding on crops like corn, beans, and strawberries. They are also known to consume algae, moss, bark, and even their own feces to recover essential nutrients like copper.
Deterring Pill Bugs from Unwanted Areas
Managing pill bug populations in unwanted areas involves modifying the environmental conditions that attract them. Reducing moisture is a primary strategy, as pill bugs cannot survive in dry conditions for long. This can be achieved by improving drainage around foundations and gardens, and adjusting irrigation schedules to allow surfaces to dry out. Watering early in the day helps ensure the ground is drier by evening, discouraging their activity.
Removing organic debris also helps deter pill bugs by eliminating both food sources and shelter. Clearing away leaf litter, mulch, rotting wood, and other plant material from around homes and garden beds makes these areas less hospitable. Sealing entry points into homes, such as cracks in foundations and gaps around doors and windows, prevents them from seeking refuge indoors. Creating physical barriers and ensuring good air circulation around plants can further reduce their presence.