Rollie pollies (also known as pill bugs, woodlice, or sow bugs) are terrestrial crustaceans, making them closer relatives to shrimp and crabs than to insects. They breathe through gills and must maintain constant moisture to survive. Because their survival hinges entirely on humidity and dampness, standard insect control methods often fail unless the underlying moisture problem is addressed. This guide focuses on eliminating the environmental conditions that attract them, alongside practical methods for exclusion and removal.
Identifying Attractants
Rollie pollies primarily seek environments offering high humidity, shelter, and a steady supply of decaying organic material. They are unable to regulate their body moisture effectively and quickly die of dehydration, compelling them to find perpetually damp habitats. Their presence is a clear indicator of localized dampness around or within a structure. Their diet consists mainly of decomposing plant matter, which provides both food and moisture. Common attractants include thick layers of mulch, heavy leaf piles, rotting landscape timbers, and grass clippings left near the foundation. During the day, they shelter under stones, flowerpots, or patio slabs to minimize water loss. When outdoor conditions become unstable, they move toward the foundation seeking stable moisture levels, often leading to indoor entry.
Environmental Modification
The most sustainable way to deter rollie pollies is to modify the outdoor environment to make it inhospitable. This begins with improving soil drainage and ensuring water flows away from the home’s foundation. Correcting the yard’s grade so it slopes away from the structure is a foundational step. For persistent moisture issues, solutions like installing French drains or buried downspout extensions can redirect water effectively.
Managing organic material near the foundation eliminates their food and shelter sources. Mulch should be kept at a depth of no more than 2 to 3 inches in flower beds and pulled back 6 to 12 inches away from the foundation walls and plant stems. This reduced depth allows the mulch to dry out more quickly, preventing the moist pockets where rollie pollies thrive. Firewood, lumber, or heavy debris should be stored off the ground and placed a distance from the house perimeter.
Reducing overall watering directly stresses their moisture-dependent biology. Inspect irrigation systems for leaks and adjust sprinklers to avoid over-saturating the soil closest to the home. Inside the home, particularly in crawl spaces and basements, using a dehumidifier or ensuring proper ventilation reduces the ambient humidity that draws them indoors. Addressing these underlying moisture problems naturally causes the local population to shrink.
Physical Exclusion Methods
Preventing rollie pollies from entering the structure involves creating a physical barrier around the entire perimeter. A thorough inspection of the foundation, doors, and utility entry points is necessary to identify all potential access routes.
Seal hairline cracks in the foundation and masonry using a flexible, exterior-grade silicone or acrylic latex caulk. For larger cracks exceeding a quarter-inch, a robust material like hydraulic cement or a concrete patch offers a durable, permanent seal. Pay close attention to utility penetrations where pipes, wires, and vents enter the home, sealing the perimeter around these with caulk or expanding foam sealant.
Exterior doors, especially those at ground level, require functional weatherstripping and door sweeps installed at the bottom edge. Gaps under doors are a common entry point and must be sealed tightly. For sliding doors, foam weatherstripping can be placed in the bottom track. Regular checks of window and foundation screens are important to ensure they are intact and securely fitted, blocking access.
Direct Control and Removal
When prevention is insufficient, active removal methods can quickly reduce the existing population. A simple, non-chemical method uses moisture-rich food traps to lure them into a collection point. A raw potato, cut in half and hollowed out slightly, can be placed cut-side down in the problem area, as rollie pollies are attracted to the dark, moist interior. The trap can be checked daily and the collected rollie pollies relocated away from the house.
For population reduction in dry areas, diatomaceous earth (DE) can be applied as a natural desiccant. DE is a fine powder that works by absorbing the protective oils from the rollie pollie’s exoskeleton, causing rapid dehydration. It is only effective when the powder remains completely dry. For heavy infestations, a targeted perimeter application of insecticide dusts or granules containing synthetic pyrethroids can be applied around the foundation.