Millipedes are common arthropods in Florida that often cause concern when they appear in or around homes, especially after heavy rains or during seasonal shifts.
These creatures are detritivores, meaning they play a role in the ecosystem by feeding on decaying organic matter like dead leaves and rotting wood. While their appearance can be unsettling, they are not aggressive and do not bite or sting like their close relatives, the centipedes. The primary safety issue with Florida millipedes involves a chemical defense mechanism they employ when disturbed.
Clarifying the Terminology: Toxic Secretions vs. Poison
Millipedes are not considered venomous because they lack fangs or stingers to inject toxins. They are not truly poisonous, though accidental ingestion could cause gastrointestinal upset. Millipedes are chemically defensive, releasing a liquid secretion from specialized glands along the sides of their bodies when threatened. This fluid is an irritant, not a venom or a systemic poison to humans.
The composition of this defensive fluid varies by species but often includes caustic compounds such as quinones, phenols, and organic acids. Some Florida species, like the Florida Ivory Millipede (Chicobolus spinigerus) or the Greenhouse Millipede (Oxidus gracilis), secrete fluids containing cyanogenic compounds that release small amounts of hydrogen cyanide gas. This chemical mixture is effective at deterring small predators, but the quantity produced is non-lethal to humans.
Common Florida Millipede Species and Appearance
Florida is home to over 50 species of millipedes, but only a few are commonly encountered in residential areas. They have a slow, undulating movement, a distinct cylindrical or rounded body shape, and possess two pairs of legs on almost every body segment.
The Florida Ivory Millipede (Chicobolus spinigerus) is one of the larger species, reaching up to three and a half inches in length, with a dark body and sometimes lighter underbelly or legs. The North American Millipede (Narceus americanus) is also large and may display a dark brown body with deep red stripes. Smaller species, such as the flat-backed Greenhouse Millipede, are notorious for invading homes through small cracks and gaps. The Yellow-Banded Millipede (Anadenobolus monilicornis), an invasive species, stands out with its dark body ringed by bright yellow bands, often seen crawling across patios and sidewalks.
Immediate Effects and First Aid Treatment
Contact with the defensive secretions results in mild, localized symptoms. The caustic chemicals can cause skin irritation, including a burning sensation, redness, and a temporary brownish discoloration. In some cases, contact may lead to mild blistering or an allergic reaction. These symptoms are usually self-limiting and resolve within 24 hours, though the skin staining may persist longer.
Exposure to the eyes requires immediate attention, as the secretions can cause significant irritation. Symptoms of eye contact include pain, tearing, inflammation of the conjunctiva, and, in rare but severe cases, corneal injury. If millipede secretions contact the skin, wash the area immediately with plenty of soap and water; rubbing alcohol should be avoided. If the fluid enters the eyes, flush them with water for at least 20 minutes, and seek medical attention immediately.
Safe Handling and Exclusion Methods
When millipedes are found inside a home, the safest removal method is to use a vacuum cleaner to suck them up, followed by discarding the bag or contents outdoors. If handling is necessary, wear gloves to prevent direct contact with the irritating defensive fluid. Rough handling should be avoided, as this triggers the release of the chemical defense.
Preventing millipede entry focuses on reducing the moisture and organic matter they seek out. Exclusion methods include:
- Remove leaf litter, grass clippings, and excessive mulch from the area immediately surrounding the foundation.
- Seal all potential entry points, such as cracks in the foundation, gaps under doors, and poorly sealed windows.
- Improve ventilation in damp spaces like basements and crawl spaces.
- Ensure exterior drainage slopes away from the structure to make the environment less hospitable.