The term “thousand legger” is a common nickname for millipedes, which are arthropods that generally live outside and play an important role as decomposers in the soil. These creatures are mostly harmless to people and property, feeding on decaying plant material rather than living tissue. When millipedes appear indoors, it is typically an accidental invasion triggered by environmental changes or attractive conditions near the home’s foundation. They seek shelter and moisture elsewhere when their preferred outdoor habitat becomes either too dry or too saturated with water.
Millipede Versus Centipede: Identification
Millipedes are often confused with their close relatives, the centipedes, but key physical and behavioral differences exist. Millipedes have two pairs of legs attached to most of their body segments, giving them a dense, leggy appearance. They move slowly and typically curl into a tight coil when disturbed.
In contrast, centipedes have a flatter body profile and only possess a single pair of legs per body segment. Centipedes are fast-moving predators that use their speed to hunt small insects.
Millipede defense mechanisms involve coiling and the release of a foul-smelling, sometimes irritating, fluid. Centipedes defend themselves with a pair of venomous fangs, or maxillipeds, located behind the head.
Environmental Factors That Attract Them
Millipedes are primarily attracted to the resources they need to survive near a home’s foundation. As detritivores, their main food source is decaying organic matter, such as heavy accumulations of leaf litter, grass clippings, and rotting wood. They thrive in areas with thick layers of mulch, compost piles, and landscape timbers.
The presence of moisture is a major factor, as millipedes have poor water retention and will quickly desiccate without high humidity. They are drawn to cool, dark, and damp environments, including wet soil and areas with poor drainage. When outdoor conditions become excessively dry, millipedes migrate toward a structure in search of life-sustaining moisture.
Conversely, periods of heavy rainfall or over-irrigation can also trigger home invasions. Saturated soil forces millipedes to the surface and higher ground, often leading them directly onto concrete slabs and foundations. They seek shelter under stones, dense ground cover, and any debris piled up against the house.
Exclusion Strategies and Habitat Control
Controlling millipedes focuses on eliminating the favorable conditions and resources that attract them to the home’s perimeter. This begins with habitat modification, specifically removing or thinning out decaying organic matter within one to two feet of the foundation. Raking back heavy mulch, leaf piles, and grass clippings exposes the soil, allowing it to dry out and reducing the primary food source and shelter.
Moisture control is equally important and involves addressing any sources of excess water near the structure. Homeowners should fix leaky outdoor faucets or pipes and ensure that gutters are clear and downspouts direct water away from the foundation. Reducing the frequency of landscape watering or switching to morning irrigation helps the soil surface dry before nightfall.
The final step is physical exclusion, which involves sealing potential entry points into the structure. Millipedes can enter through tiny cracks and gaps in the foundation, door thresholds, and basement windows. Applying caulk to seal these openings and installing door sweeps on all exterior doors will prevent them from gaining access.