We came across this what I believe is the Fox Moth Caterpillar a few years ago as we were walking by the Ladybower Reservoirs in the Peak District. Fully grown caterpillars are up to 7cm in length. They have long brown hairs on the sides of the body and shorter dark orange hairs on the upper surface. Young caterpillars are darker brown with light orange bands along the body. The caterpillars hibernate fully grown, but emerge to bask in the spring sunshine before pupating in April.