Perhaps best known for its seemingly countless legs, the centipede resembles an insect but is in fact a non-insect arthropod; class Chilopoda. Its multiple body segments, each connected to a pair of legs, contribute to its unusual birth-to-maturity development.
Centipedes hatch from eggs. When they first enter the world, they look like miniature versions of the adults they will soon become. Therefore, their metamorphosis is -- unlike that of a caterpillar -- incomplete. As they mature, they, like all arthropods, shed their skin multiple times, a process called molting. Most centipedes grow new pairs of legs with each molting.
Immature centipedes are called nymphs. Each time a centipede undergoes molting, it enters a new stage of its life cycle. These stages, called instars, are most easily differentiated by the number of legs each one features. After one molting, a typical house centipede has 10 legs, and after three is has 18; mature adults -- which can live up to five years -- have about 30.
Centipedes eat insects, and the largest can even eat mice. They have a pair of venomous jaws, which evolved from a pair of legs and which centipedes use to kill their prey. Centipedes qualify as pests because they sometimes bite people, especially when they're handled. These bites may hurt, can cause allergic reactions, especially in children, and can lead to ulceration and necrosis. However, usually they just hurt, and then itch as they heal.