Indian Stick-insect

• There are hardly any males: the species keeps going by parthenogenesis, and the populations consist almost entirely of females producing clones of themselves.
• It changes colour through the day, darkening at night and paling in the light, by moving pigment granules in its skin.
• If it loses a leg, it regrows it over the following moults, although it usually ends up slightly shorter than the original.
• It is the laboratory stick insect par excellence and probably the most widely reared insect in the world in schools and universities.
• Almost all cultured populations are parthenogenetic and consist only of females: males are extremely rare and, when they do appear, are usually sterile. That makes it possible to maintain cultures indefinitely from a single individual.
• It changes colour with light, temperature and humidity, darkening at night and lightening by day, by shifting pigment granules within the epidermis.
• It plays dead: faced with a threat it drops to the ground rigid and motionless, legs pressed against its body, and can stay that way for a long while.
• It has been used for decades as a model in studies of legged locomotion, and its coordination patterns have inspired the control of six-legged walking robots.
• It can autotomise a leg to escape and partially regenerate it over the following moults.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat & environment

Shrubs and scrub of southern India; spread worldwide in captivity

Sources consulted: Cruse, trabajos sobre coordinación de patas en Carausius; Bässler, Neural Basis of Elementary Behavior in Stick Insects; Phasmid Study Group