Millipedes are common occasional pests that sometimes invade buildings, particularly when the weather turns hot and dry. While millipedes sometimes enter in large numbers, they do not bite, sting, or transmit diseases, nor do they infest food, clothing or dry, structurally sound wood. Millipedes vary in both color and size. The most common species that invades buildings is the" garden millipede", which is brownish-black in color and about one inch long. Although millipedes are often called "thousandleggers", they actually have far fewer legs, but each body segment has two pairs of very short legs. When disturbed, millipedes often curl up into a "C" shape and remain motionless. They crawl slowly and protect themselves by secreting cyanide-like compound that has an unpleasant odor . Some people confuse millipedes with centipedes, which look somewhat similar. Centipedes have only one pair of legs per body segment and the legs are usually longer than those on millipedes. Centipedes also tend to move about more quickly than millipedes.
Pesticides are typically a short-term solution to a long-term problem. Emphasis should be placed first on reducing conditions and access points favorable to millipede invasions:
Minimize Moisture, Remove Debris - The most effective, long-term measure for reducing entry of millipedes (and many other pests) is to reduce excess moisture and hiding places, especially near the foundation.
Seal Pest Entry Points – Seal cracks and openings in the outside foundation wall, and around the sills of doors and basement windows. Install door sweeps on all exterior entry doors, and apply caulk along the bottom outside edge and sides of door thresholds. Seal expansion joints where outdoor patios, sunrooms and sidewalks abut the foundation. Expansion joints and gaps should also be sealed along the bottom of basement walls on the interior to reduce entry of pests and moisture from outdoors.
Chemical control - Application of insecticides along baseboards and other interior living areas of the home do not really stop millipede invasions. Once indoors, millipedes end up in kitchens, living rooms, etc. and soon die from a lack of moisture. Remove them with a vacuum cleaner or broom.
For additional information about millipedes see: http://www.ces.ncsu.edu/depts/ent/notes/Urban/millipedes.htm