The creature commonly known as the “thousand legger” often inspires curiosity or concern when found in and around the home. While the name suggests a high leg count, this term describes the millipede, an arthropod belonging to the class Diplopoda. Millipedes thrive in damp, dark environments and are associated with high moisture and decaying organic material. Identifying this segmented animal is necessary to understand if its presence is beneficial or a nuisance.
Distinguishing Millipedes from Centipedes
The distinction between millipedes and centipedes is important because their behaviors and potential risks are entirely different. Millipedes have a rounded or subcylindrical body shape and move slowly. Their defining feature is having two pairs of legs attached to almost every visible body segment, giving them a dense, brush-like appearance. They are primarily detritivores, consuming dead and decaying plant matter.
Centipedes, by contrast, have a visibly flattened body profile and move much more quickly. They have a single pair of legs per body segment, with legs extending outward from the sides. When threatened, a millipede curls into a tight spiral and may release a foul-smelling chemical secretion. Centipedes are predators that use a venomous bite to subdue their prey, reflecting a completely different ecological role.
The Beneficial Role of Millipedes
In natural outdoor settings, millipedes function as nature’s recyclers. As primary detritivores, they feed on decaying organic matter, such as dead leaves and rotting wood. By consuming and fragmenting this material, they accelerate decomposition, a foundational aspect of healthy soil ecosystems. This breakdown prevents the accumulation of plant litter that could suppress plant growth.
The millipede’s digestive process returns locked-up nutrients back into the soil, facilitating the cycling of elements like nitrogen and phosphorus. Their feeding activity also contributes to soil aeration and the formation of humus, which improves soil structure and water retention. In gardens and yards, millipedes support fertility and the overall health of the ecosystem.
When Millipedes Cause Problems
Millipedes transition from beneficial decomposers to household nuisances when their outdoor habitat becomes unsuitable. The most common trigger for migration is extreme weather, such as prolonged drought or excessive rain. Both conditions drive millipedes from damp soil, forcing them to seek shelter and moisture in drier locations, which often leads them toward building foundations and interior spaces. Once inside, they gravitate toward moist areas like basements and crawl spaces, but they cannot survive long in a dry indoor environment.
Millipedes do not consume wood or household fabrics and pose no structural threat. However, they can become a garden pest under specific circumstances, occasionally feeding on tender plant material or damaged seedlings. The species’ defensive secretion, which can contain chemicals like benzoquinones, can cause mild skin irritation or leave a temporary stain if they are crushed.
Managing Millipedes in and Around the Home
Effective millipede management focuses on altering the environmental conditions that attract them, rather than relying on chemical treatments. The most important step is controlling moisture, as millipedes are highly dependent on damp environments. This involves fixing leaky plumbing, ensuring gutters divert water away from the foundation, and using a dehumidifier in basements. Watering lawns and gardens in the morning is also helpful so the ground can dry out before millipedes become active at night.
Habitat Reduction
Habitat reduction involves removing organic debris that provides shelter and food near the house perimeter. Clear leaf piles, grass clippings, and mulch away from the foundation walls to create a dry, bare zone. Stored firewood or lumber should be elevated off the ground and kept away from the structure.
Physical Exclusion
Physical exclusion prevents entry by sealing potential access points. This includes sealing cracks in the foundation, gaps around utility lines, and openings beneath doors with weatherstripping or caulk.