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What Causes Millipedes To Invade Homes By The Hundreds Or Even Thousands, And How Can Infestations Be Eliminated?

The soil-dwelling arthropods known as millipedes were among the first terrestrial organisms to appear on earth around half a billion years ago, and much like earthworms, millipedes provide an essential ecological service by breaking down plant waste and aerating soil. Like insects and arachnids, millipedes belong to the phylum Arthropoda, and more than 7,000 millipede species have been documented worldwide, 1,400 of which can be found in the US and Canada. Unlike insects and arachnids, millipedes and centipedes belong to the subphylum Myriapoda, making them more closely related to marine organisms.

Millipedes are active within moist soil, and they are commonly spotted beneath objects like stones, bundles of plant litter, and landscaping ornaments where they maintain moist living conditions. Given their slow movements and dependence on high moisture conditions in order to survive, it may seem unlikely for millipedes to appear within homes. However, it is not uncommon for millipedes to invade homes in large numbers in order to seek refuge from bouts of disagreeable weather. Millipedes are well known for being particularly common nuisance pests within homes and buildings in Houston where millipede outbreaks affect entire neighborhoods.

Every few years, millipede populations become overabundant in eastern Texas where homeowners often remove hundreds or even thousands of millipedes from their home in a single day. Last year, millipedes became so abundant in Houston that some affected homeowners found it impossible to completely remove the pests from their home. Earlier this year in May, Houston extension entomologists were already being bombarded with residential complaints concerning indoor millipede pests, specifically the greenhouse millipede (Oxidus gracilis).

The greenhouse millipede is the most commonly managed millipede pest in Texas, and in order to secure moist conditions during bouts of dry weather, these millipedes will not hesitate to invade homes where they gravitate toward bathrooms, basements and kitchens. Greenhouse millipedes also invade homes to seek high ground during bouts of excessive rainfall, especially when flash-flooding occurs. In addition to being a tremendous nuisance to homeowners, millipedes also emit a foul stench that cannot be avoided when large numbers become concentrated within homes. While millipedes are not considered medically harmful, they do secrete caustic defensive fluids that cause skin damage. Millipedes do not typically survive long within homes due to inadequate moisture content indoors, but heavy infestations warrant professional pest control intervention.

Have you ever found millipedes within your home?