Grey Dagger caterpillar

I was opening the Phil Stead hide over the weekend and picked up this colourful caterpillar on my sleeve.  It has an interesting little 'hump' a little way behind its head, at the front of the abdomen and is covered with hairs, which are known as 'seta.'

This is the larva of the Grey Dagger moth (Acronicta psi) which is quite common.  As the name suggests the moth itself is quite grey, but has some relatively smart, darker markings, which help to give it its name.

The individual in the picture above came to a light trap at the workshop on the 24th June this year, although it could be either a Grey Dagger, or a Dark Dagger moth (Acronicta tridens).  The two look very similar in adult form (the caterpillars are very different) and to identify them confidently requires inspection of the genitalia.

The caterpillar will eat a variety of broadleaved trees and shrubs, including hawthorn and blackthorn.  It will pupate overwinter, in a silk cocoon under loose bark or in a crevice somewhere amongst rotting wood.  A good reason to leave some areas of rotting wood in the garden.