Millipedes are common household pests that are brownish-black in color and that can grow to about an inch in length. Also known as “thousand-leggers,” these pests don’t actually have 1000 legs. They do, however, have 2 pairs of very short legs on each segment of their body. They are often confused with centipedes which only have 1 pair of legs per body segment. Millipedes crawl slowly and will curl into a “c” shape and remain motionless when they are disturbed. They can also secrete an unpleasant smelling odor.
Millipedes overwinter as adults and lay their eggs in the spring. They can live for several years. They are scavengers, eating primarily decomposing vegetation. They are attracted to cool, dark, moist environments (like compost piles, flower beds, mulch, rotting logs, and under rocks and logs). When the weather is hot and dry or there is an overabundance of water, they will emerge and make their way into your home in search of moisture or shelter. They can infest in large numbers but they don’t bite, sting, transmit diseases, infest food, clothing, or even dry wood.
Millipedes will come indoors for a variety of reasons. When the weather is hot and dry, they will invade your home in search of moisture. When conditions are extremely wet they will be forced to higher ground (e.g. concrete slabs, foundations, and siding). In the fall they migrate in search of places to overwinter. In these conditions, they will make their way into your home through door thresholds (especially garage and sliding glass doors), through expansion joints, and through voids in concrete block walls. Millipedes cannot survive indoors more than a day or two.
Now that you know more about millipedes and what attracts them to your home, what can you do to keep them from infesting your personal space?
- Get rid of debris. Get rid of any leaves, grass clippings, heavy layers of mulch, wooden boards, boxes, stones, etc. that may be laying on the ground near your foundation. Keep mulch cover light and at least 6 to 12 inches away from foundations. Use inorganic mulch if possible.
- Eliminate moisture. Keep water from accumulating near foundations, inside basement walls, and in crawlspaces. Keep gutters and downspouts clear of debris. Use splashguards to reduce puddling. Consider installing gutter guards to prevent clogs. Repair leaking spigots outside. Prevent puddling near AC drip lines. Dehumidify your crawlspace and basements with dehumidifiers, adequate ventilation, and sump pumps. Consider enclosing your crawlspace for additional protection.
- Lawn care. Aerate your lawn to dethatch and make the soil less attractive to millipedes. Keep grass mowed close. Avoid overwatering the lawn and set sprinklers up on an appropriate schedule.
- Seal entry points. Eliminating entry points is the best way to keep millipedes from sneaking in. Seal cracks and openings in foundation walls and around door and windowsills. Install door sweeps on all exterior doors. Apply caulk on the bottom outside edge and side of door thresholds. Seal expansion joints where patios, sunrooms and sidewalks touch foundations and along the bottom of basement walls.
Chemical treatments indoors are usually not very effective against millipedes. If you have them inside just sweep or vacuum them up and dispose of them. Chemical treatments outdoors can help keep them from crossing the threshold inside. If you have a problem with millipedes, consider calling a professional pest control company for an evaluation and treatment plan.