Millipedes do not bite or sting, nor do they do any damage to stored food, structures, or furniture. However, there are some species of millipedes that excrete a defensive fluid that irritates the skin of people who handle them or otherwise come into contact with those toxic millipede species.

Since the pests are most active at night, their appearance can scare homeowners moving boxes or other items. Millipedes also move in large numbers, so they can become a major nuisance and cause quite a fright to unsuspecting people or pets. But, since millipedes feed on and thus decompose organic matter, they are actually very beneficial to the environment.

When they come to a home, millipedes gather on porches and patios. They climb the foundation of the home and they often find entryways such as basement doors and windows, crawlspace vents, doors with missing weather stripping, garage doors

Millipedes normally live outdoors in damp places. Around homes they live in flowerbeds and gardens. People often find millipedes under:

Mulch
Piles of dead leaves and grass clippings
Structures like dog houses and storage sheds
Crawlspaces are excellent millipede habitats. There are often boxes of stored items and pieces of lumber on the ground under a home. The millipedes can feed on dead leaves that have blown into the crawl space or small pieces of damp or decaying wood.

These pests closely resembles centipedes - they have long, slender bodies with many pairs of legs on each side. Millipedes can grow up to 10.5 inches in length (27 cm long), but can be as small as 0.12 inches (0.32cm).  

Millipedes, unlike centipedes which are predatory arthropods, do not eat other insects. These pests feast on decaying wood, dead leaves & foliage, and other small particles that they can find.

In an emergency, a vacuum cleaner or a shop-type vacuum can be used to remove millipedes from walls and floors. When the situation gets bad, many homeowners call for help.