There are however, some millipedes, such as O.gracilus, that are flattened. Every millipede has two pairs of legs attached to each apparent body segment.
Most millipedes are brown or black, but some species are orange or red.
Pillbugs can be distinguished from sowbugs because pillbugs are able to roll themselves up into a ball when alarmed, and they lack the two prominent tail-like appendages. As a household pest, millipedes are more of an annoyance or nuisance, rather than an indoor-breeding pest that causes destruction. Millipedes normally are found outdoors where they feed on damp and decaying wood, organic material, and will also feed on tender roots and green leaves that have fallen to the ground. Millipedes are not poisonous, but many species have repugnatorial glands capable of producing mild acids which may produce allergenic reactions in sensitive individuals. There are at least 1,000 species of millipedes in the United States, a few of which are capable of squirting their unpleasant fluids over a distance of several inches.