Sow bugs, often mistakenly called pillbugs or woodlice, are common household invaders. These creatures are crustaceans, not insects, and are generally a nuisance rather than a threat since they do not bite, sting, or transmit diseases. The primary motivation for eradication is their presence indoors, which usually signals a larger issue outside the home. Effective control requires understanding and disrupting the specific environmental conditions these animals need to thrive.
Understanding Why Sow Bugs Are Present
Sow bugs are highly dependent on moisture because their gill-like breathing apparatus requires continuous high humidity (typically above 75%) to prevent desiccation. They are nocturnal and seek out dark, damp environments during the day, often hiding under rocks, wood, or dense leaf litter. If the outdoor habitat becomes too dry or overcrowded, these crustaceans migrate in search of new moist refuges.
Their diet consists primarily of decaying organic matter, such as dead leaves and rotting wood, making mulch beds and compost piles near a foundation attractive feeding and breeding grounds. An indoor presence is usually accidental, but it indicates a moisture problem, such as a leaky pipe or a damp crawl space. Finding sow bugs inside suggests a large population is established immediately outside the home’s perimeter.
Natural and Physical Removal Methods
Immediate removal of sow bugs found indoors can be accomplished simply by vacuuming them up. Since these crustaceans cannot retain water, environmental manipulation is a powerful control strategy. Using fans and dehumidifiers in damp areas like basements and crawl spaces quickly reduces humidity levels, forcing the sow bugs to dehydrate and die within a few days.
Simple trapping methods can also reduce their numbers. Sow bugs are attracted to moisture and food sources, so a temporary shelter can be used to lure them. Examples include a rolled-up, damp newspaper or a hollowed-out piece of fruit or potato placed cut-side down. Collect and discard these traps the following morning before the sow bugs disperse.
Targeted Insecticidal Treatments
When natural methods prove insufficient for a severe outdoor infestation, targeted insecticidal treatments can be employed. Dust formulations are highly effective because they work as desiccants, disrupting the sow bug’s ability to retain moisture. Diatomaceous earth (DE) uses sharp microscopic edges to pierce the exoskeleton and cause dehydration.
Applying a fine layer of DE along foundation cracks creates a perimeter barrier, though its effectiveness is lost when wet. Boric acid dust can also be used, acting as a stomach poison, but it requires caution around children and pets. Liquid residual insecticides, often labeled for perimeter control, should be sprayed three feet up the foundation and three feet out onto the surrounding soil to establish a protective chemical barrier.
Exterior and Interior Exclusion Strategies
The most lasting solution is to implement structural and environmental exclusion strategies that deny sow bugs the necessary habitat. This process starts with moisture control, involving diverting downspouts away from the foundation and ensuring the soil slopes away from the home for proper drainage. Using a dehumidifier indoors to maintain relative humidity between 30% and 50% makes the environment hostile to their survival.
Exterior habitat modification is equally important, requiring the removal of organic debris that serves as food and shelter. This includes:
- Clearing leaf litter.
- Keeping firewood stacked off the ground and away from the house.
- Replacing organic mulch near the foundation with gravel or a different coarse material.
Finally, sealing all potential entry points is necessary. Use caulk to close foundation cracks and install weather stripping and door sweeps to eliminate gaps.