Survival behaviour

The female takes up an unusual aggressive  posture. It will thrash its hind legs and  latch onto the animal that is attacking it.

If you think this adult stick insect is defenceless you are mistaken. Look at its appearance as it mimics a scorpion. If the looks do not fool the hungry predator its reactions will certainly make it think twice about attacking.

Both the male and female stick insects play dead and are extremely convincing at it.
Click to see a 120Kb video of the male and the female in action.

If playing dead is not enough to convince the predator the female has one very incredible response.

It turns its back to the aggressor(click here to see a 120kb movie) and starts to thrash its hind legs (click here to see a 120kb movie). It grabs onto whatever is attacking it, and digs the hooks on its legs into the skin. At this point the startled predator is happy just to shake the insect off its beak or head and find some other food source.
The hooks on the powerful hind legs of the female can penetrate the skin enough to make it very uncomfortable for any menacing animal.

The spikes on the female's body look very menacing and may irritate animals enough so as to leave the insect alone.

Suggest why the female is so heavily fortified with defensive strategies while the male has relatively few?