Length 8 -9 cm. Their hairs can cause a violent itching skin allergy in some people. It feed on Larix, Betula, Salix and Rubus species. Though from the name you would think it's main food plant was Oak, total misnomer as the name come from the fact that the Chrysalis looks like an Acorn from the Oak tree. It can take upto 2 years for the full life cycle dependent on warmth of the climate. In the south they over winter once as a small larvae, up here in the north a second winter of hibernation as a large larvae then pupation in May and emergance in July/August.
It is found in Europe and the British Isles.
Related spotting: http://www.projectnoah.org/spottings/905...