Worldwide there are more than 2,500 different species of Stick Insect (Phasmatodea), and here in Hong Kong we have about 10.
They can be quite different sizes and shapes. Some have wings like this one above.
The largest recorded is 55cm, and they do get big here, as modeled by my friend Dan below...and he does have quite a big head.
Since they are limited in numbers and cannot always find each other the females can reproduce by parthenogenesis; ie without mating. they simply lay eggs on the ground, where they can be quite safe.
This one has quite a devilish look!
They moult 5-6 times before developing into an adult. And as an update to their defence mechanism of "dropping" legs when attacked, i have learned that they can regrow this leg, when they moult! which is really quite rare and astonishing.
The insect above is green and red, whilst the twig insect below is quite different.