This is the wonderful violin mantis. This nymph is very small, and I must add, not a Hong Kong native.
This is Gongylus gongylodes, also known as the wandering violin mantis, ornate mantis, or Indian rose mantis, and it is an insect of the order Mantodea- or a Praying Mantis to you and me.
These nymphs were tiny, only a few cm long...and here a close up.
Characterized by extremely slender limbs with large appendages. It is not a particularly aggressive species and often kept as a pet by hobbyists.