Approximately 3000 species of Phasmids exist in the world, about 30 of which live in the United States. Unlike many insects, they make superb pets. Stick-insects prefer to have their cages and leaves misted with a spray bottle, although care must be taken not to drown the fragile nymphs. Others do require heat or humidity to be successful. A phasmid will usually live from one to two years, depending on the species.
Some species are completely or partially parthenogenetic.
Phasmids have exoskeletons, meaning that the apparatus which provides structure to their bodies is on the outside. Females commonly molt 6 times, and males 5. This means that females have 7 instars, and males have 6. Instars are the stages during the life cycle between molts. Sometimes when Phasmids are disturbed, they will lay motionless for hours.