ARTHROPODS WITH A MYRIAD OF LEGS
Millipedes are a common outdoor arthropod in the Bay Area, but not usually seen indoors in high numbers. Possible means of introducing these creatures in the home include potting soil for indoor plants and cracks in the home or open doorways, especially near leaf litter or old wood. Millipedes do no harm to property and pose no risk to public health, and typically die quickly in a house because moisture levels are too low.
Millipedes and centipedes are not insects (which have six legs) but are both arthropods of the subphylum Myriapoda, which means 10,000 feet. Despite the names, millipedes have 40 – 400 legs and a centipede has between 30 and 354, depending on species. A millipede has two pairs of legs per body segment, moves slowly and eats vegetation. The body is cylindrical and it curls up when disturbed. A centipede has one pair of legs per body segment, moves quickly and is predaceous on small insects and other arthropods. It has a flattened body and never curls up. Some centipedes have a venomous bite. They also do not do any damage in a house, and can provide beneficial pest control.
Rarely do millipedes or centipedes need management. If large numbers are entering a house, vegetation near the edges can be cleared and screens and gaps under doorways checked and repaired. Reducing moisture will also limit their numbers. Most of the time, we can enjoy millipedes and centipedes outdoors as part of the diversity of fauna in our yards and gardens.