Small Eggar Eriogaster lanestris
Wingspan 30-40 mm.
Formerly quite common, this is now a scarce and local species, due mainly to the gradual destruction of its favourite habitat, hedgerows.
The adults, which fly in February and March, are seldom seen, but the larvae, when present, live gregariously in silken webs on the foodplant, hawthorn (Crataegus) and blackthorn (Prunus spinosa).
It is now restricted to a few scattered colonies in England and Ireland, and a few localities in Wales.