Millipedes are terrestrial arthropods belonging to the class Diplopoda, characterized by their elongated, segmented bodies. They are often called “thousand-leggers” because they have two pairs of jointed legs on most body segments. These creatures play a beneficial ecological role as detritivores, primarily feeding on decaying organic matter such as leaf litter and rotting wood. By consuming this material, they help break down matter and return nutrients to the soil.
Assessing the Threat
The presence of a millipede in the home may cause alarm, but these arthropods pose no significant risk to humans or household pets. Millipedes are not venomous, nor do they possess fangs or stingers, and they are not known to transmit diseases. Their primary defense mechanism involves coiling up into a tight spiral.
A few species can secrete a defensive fluid from specialized glands, called ozopores, when roughly handled or stressed. These secretions often contain compounds like quinones, which act as a chemical repellent. Contact with this fluid can cause temporary skin irritation, minor blistering, or a yellow-brown discoloration of the skin. If accidental contact occurs, the affected skin should be washed immediately with soap and water.
Distinguishing Millipedes from Centipedes
Millipedes are often confused with centipedes, which belong to a different class of arthropods (Chilopoda). Distinguishing the two involves observing physical and behavioral characteristics. Millipedes have a cylindrical body shape and two pairs of legs per segment, moving slowly and relying on defensive secretions or coiling.
Centipedes, conversely, have a flattened body profile and only one pair of legs per segment extending out from the sides. They are quick, active predators. Centipedes possess modified front legs, called forcipules, which inject venom, making their bite painful to humans.
Why Millipedes Enter the Home
Millipedes spend their lives in moist, dark environments outdoors, such as beneath mulch, under rocks, or in leaf piles, where they can find decaying vegetation to eat. Their migrations indoors are typically accidental, driven by environmental factors that make their outdoor habitat unstable. They seek shelter when conditions become either excessively wet, such as after heavy rainfall or flooding, or conversely, too dry, like during an extended drought.
These movements are driven by the need to locate a more stable, damp refuge, rather than seeking food inside the structure. Once inside, they gravitate toward areas that mimic their preferred habitat, often found in basements, crawlspaces, or ground-level rooms with high humidity. Since indoor environments lack the high moisture and organic matter they need to survive, millipedes found inside usually perish quickly due to desiccation.
Safe Removal and Prevention
To address an indoor millipede presence, the most direct approach is manual removal, as they do not survive long inside a dry home. Individual specimens can be swept up with a broom and dustpan or easily vacuumed, and then safely disposed of outdoors away from the foundation. Using insecticides inside is generally ineffective because it does not resolve the underlying environmental factors drawing them in.
A long-term strategy focuses on modifying the outdoor environment to make the home perimeter less attractive to these moisture-loving creatures. This involves two main steps: reducing outdoor harborage and controlling moisture and entry points.
To reduce harborage, clear away moisture-retaining materials like excessive leaf litter, grass clippings, and thick layers of mulch that are in direct contact with the foundation. Moving woodpiles and storage items away from the house also eliminates potential hiding spots.
The next step involves moisture control and sealing entry points around the structure. This can be achieved by:
- Fixing leaky faucets or pipes and using a dehumidifier in damp areas like basements to reduce indoor humidity.
- Inspecting the home’s exterior to seal potential entry routes, such as caulking cracks in the foundation.
- Ensuring that door sweeps and weather stripping are properly installed on all ground-level doors and windows.