They are generally round in cross section and, with the exception of the first four or five, all of the body segments possess two pairs of legs. They are relatively slow moving, and feed on fungus and decaying plant material. At times, they can be a pest to vegetables or other plants in greenhouses. Their antennae are longer, they are more flattened in cross section, they have one pair of legs per body segment and they can move rapidly. They are beneficial in that they are predators of other arthropods.
Centipedes are nocturnal and actively seek dark shelter if exposed.
The first pair of legs possess venom glands, which they use to subdue their prey. Sowbugs are highly dependent on moisture, which accounts for their common association with damp habitats. Generally, they feed on decaying plant material. They will occasionally feed on young plants in greenhouses and gardens but impact in these situations is minimal. They are not common and live under stones, in damp soils rich in organic matter, and in rotting wood.