
	Identification Scientific Name: Heteropteryx dilatata Common Names: Stick insect, leaf insect, phasmid, walkingstick Classification Class: Insecta Order: Cheleutoptera Family: Phasmatidae Genus: Heteropteryx Species: dilatata

Habitat
Stick insects and leaf insects are especially common in tropical areas. Some species occur in temperate regions. They are most abundant in Australia and southeast Asia.

Profile
The word phasma means " apparition ", which in a sense says it all. These strange insects seem to be as much a part of the inanimate world as they are of the living one. Leaf insect, stick insect and walkingstick: all names that bring the plant and animal worlds together.

To assure their survival, all 2 000 or so phasmid use a similar strategy: they blend into the background by mimicking leaves or sticks to perfection. The Heteropteryx dilatata is also one of the largest insects in the world.

Not content to modify their appearance, stick insects also have adjusted their locomotion accordingly. They always move very slowly, in fits and starts, like a branch or twig twisting in the wind. Most phasmids can remain completely motionless for hours on end, in such a state of torpor that they seem virtually to be an integral part of the plant on which they are resting.

Though most stick insects rely on this passive camouflage to avoid predators, some of the larger species have large spines on their hind legs which can serve as aggressive tools of defence against predators, as well as in competition with other males. Yet others have a defensive corrosive chemical spray emitted from a special gland.

Most stick insects are green or brown. Some, however, can be more colourful changing colours according to the degree of light, temperature or humidity.

Stick insects continue to fascinate researchers. For instance, in the immature stage, they are able to regenerate severed limbs.

Another intriguing feature: many species are capable of parthenogenic reproduction (i.e. the ova develop without fertlization into females only, which can in turn mature and repeat this process). In these species, males are virtually non-existent.

Males and females of a same species can be so different that entomologists can have a hard time pairing them up to classify them as a species.

Stick insects are easy to raise in captivity and, in many parts of the world, they are becoming increasingly popular as pets. Almost as exciting to keep as an extra-terrestrial . . . and certainly less risky!

One species of phasmid looks so much like a leaf that phytophagous (leaf eating) insects will often try to feed on them!

Don't even think about stretching out under a tree infested with these stick insects -- it would be dripping with their chemical spray, which can cause considerable pain.

In some species of stick insects, coloration even varies with the day and night cycles. They become dark at night, and lighter during the day!

For instance, in a typical culture of Carausius morosus stick insects,

there may be only 2 to 7 males for 3 000 females!