The eggs may remain dormant for over a year before hatching. In some parts of the tropics, stick insects may be so abundant that eggs falling out of the trees may sound like rain on a tin roof. Some walkingsticks are sold as pets. They are easy to rear if kept in a warm environment with fresh foliage from their host plant. Glands located on the thorax of many species can produce a foul-smelling liquid that repels predators.
Some species can even regenerate lost legs.
These are the only insects able to regenerate body parts. Males may be uncommon or unknown. Some phasmids change color with changes in temperature, humidity, or light intensity. Pigment granules in the epidermis disperse at night or on cool days, darkening the cuticle and absorbing more heat. A number of people in the UK and USA are keen to exchange stick-insects, and presumably eggs.