CATERPILLARS are one of those creatures that, as a ranger, I seem most frequently presented with.

I suppose they are easily captured and some are weird and fantastic shapes that attract and intrigue. To my shame, caterpillars are one of those creatures I find hardest to identify.

This is not really helped by the fact there are more than 5,000 different species of moth and butterfly in Britain with each having a caterpillar stage to their life cycle.

Even within the butterfly and moth family, caterpillars of different species can look incredibly similar requiring a microscope to tell apart and none of them look anything like the butterfly or moth they eventually turn into.

Caterpillars are basically the feeding stage of the butterfly or moth's life cycle.

All caterpillars have a hardened head. This is fitted with strong jaws with the lips of the mouth beneath these having silk producing glands. These produce liquid silk that dries in the air to produce tough strands of silk. This silk is used to produce shelters from leaves, escape lines and the material to construct their cocoon.

The body of every caterpillar has 13 segments. Only the first three have true legs. These end in grasping claws, which the caterpillar uses more for the holding and feeding food into its mouth than for walking. The other segments of the caterpillar's body have leg-like structures but these are not technically seen as legs.

Nethertheless, they are very effective at allowing the caterpillar to move in a waddling sort of way or, in the case of the Geometridae family, in a strange looping sort of motion. These short, stumpy legs have tiny hooks at the end and can secure a caterpillar quite firmly to a plant.

The rearmost segments, the false legs, are a little more specialist and have a strong clasping action.

The bodies of the caterpillars are covered in hairs and these give the caterpillars their distinctiveness. Some have tiny insignificant hairs while others can have spectacular and diverse hairstyles.

The more boldly patterned and coloured ones' aim is to startle and confuse would-be predators or warn them off with fearsome poisonous defences. In other caterpillars, their colouration and hair arrangements try to blend them into the background or to make them look as inedible as possible.