While up at the Down on 8 April, our ranger Nick Beale spotted this large caterpillar which was 55 mm long and around 10 mm in height (including hairs).
After investigation, Nick concluded that it is the caterpillar of an Oak Eggar moth, Lasiocampa quercus. The adult is a large, furry moth that can be seen flying in late spring and summer. The caterpillars appear in mid-late summer, are inactive over winter, then start feeding again in spring. In early summer, they pupate on the ground, amongst vegetation, in a tough brown cocoon. The hairs on this particular caterpillar are not an irritant but some species are so please just look, take a photo, draw or sketch, but don’t touch.
You can read more about this particular moth on the Wildlife Trusts website.