The curious case of harmless millipedes gathering in homes

Have you seen something like this crawling around your house lately?

Millipede. Photo credit: Gary Alpert, Harvard University, bugwood.com, #5380248

Or maybe something like this:

Dead millipedes on sticky trap. Photo credit: Gary Alpert, Harvard University, bugwood.com, #5380246

These are examples of millipedes, small arthropods that prefer moist habitats outdoors and are important nutrient recyclers in soil and leaf litter. Millipedes (a name meaning “thousand feet”) are not insects or worms, but belong to the order Diplopoda in the subphylum Myriapoda. The name Diplopoda can be broken down into “diplo-,” meaning two or double, and “-poda,” meaning foot. This name references the two sets of legs most millipedes have on each body segment. Having so many legs can make a millipede appear to have a thousand legs, but common species have less than 400 legs. Millipedes are strictly herbivores, and enrich soil as they digest organic material into smaller pieces. Native species of millipedes commonly inhabit leaf piles, mulched areas, and other moist areas of your yard where there is decaying plant material. These native species do not aggregate in homes. The millipedes you may be seeing in your homes this time of year are either the rusty millipede (Trigoniulus corallinus) or the yellow-banded millipede (Anadenobolus monilicornis).

Both millipede species are introduced to the U.S. and swarm in homes around October for unknown reasons. These millipedes do not bite or sting, and die within 24 hours of entering a building. Millipedes breathe through holes in their bodies called spiracles, which they cannot close, and they lose water through their spiracles and die in drier environments like your home. This also means they can’t lay eggs in your home, so no need to worry about a true infestation even if you see a lot of these.

You can keep millipedes out with tightly sealed windows and good weather stripping on doors. Sweep dead millipedes into a dustpan and discard rather than vacuuming as they have a disagreeable odor that can taint your vacuum cleaner. While it may be disconcerting to see a pile of dead millipedes, keep in mind they won’t harm you or your property and won’t be around for much longer to bother you.

Read more about yellow-banded millipedes here: http://trec.ifas.ufl.edu/mannion/pdfs/Yellow-bandedMillipede.pdf