Pill bugs, often called “roly-polies” for their ability to curl into a tight ball when disturbed, are creatures often encountered in gardens and homes. Despite their common name, these segmented animals are not insects. They are crustaceans, related to shrimp, crabs, and lobsters, and are among the few crustaceans that have fully adapted to living on land. These widespread organisms can be found across the globe, including throughout the United States.
Understanding Their Habitat Needs
Pill bugs require specific conditions to survive. Moisture is essential for these terrestrial crustaceans because they breathe through gill-like structures. While they cannot survive submerged, their gills must remain damp, making them dependent on humidity. They perish in dry environments within days if moisture is unavailable.
They also seek dark, sheltered locations, often being nocturnal to minimize water loss. Their segmented bodies are not waterproof like an insect’s exoskeleton, leaving them vulnerable to desiccation. As scavengers, pill bugs feed on decaying organic matter like dead plants, fungi, and leaves. This diet explains their presence in areas rich in such materials, as these spots provide both food and damp, dark shelter.
Outdoor Hiding Spots
Outdoors, pill bugs are commonly found in places that meet their requirements for moisture, darkness, and decaying organic matter. They frequently hide under rocks, logs, and leaf litter, which offer dampness and protection. Mulch, compost piles, and garden debris are also favored locations, as these materials retain moisture and serve as a direct food source.
Potted plants provide another common outdoor dwelling, especially where soil remains moist. They may also burrow below ground to escape heat and dry conditions. Areas around the edges of buildings or under elevated objects like boards and trashcans often harbor pill bug populations because these spots are damp and secluded. Reducing such habitats around foundations can help manage their numbers near homes.
Indoor Encounters
Pill bugs occasionally venture indoors, though their presence is typically accidental. They often enter buildings when seeking moisture or shelter, especially during dry or cold weather, or when their outdoor habitat becomes oversaturated. Their reliance on high humidity means they generally cannot survive indoors for more than a few days without moisture and food.
Common indoor locations where pill bugs might be found include damp basements, crawl spaces, laundry rooms, and bathrooms, especially under sinks. They can enter through cracks in foundations, gaps under doors, or unscreened vents. While their appearance indoors can be a nuisance, pill bugs are considered harmless to humans and pets.