The Feathered Thorn (Colotois pennaria) is a moth of the family Geometridae. It is found throughout Europe and the Near East.

The forewings of this species are basically brown but individuals vary greatly in tone from drab light brown to much richer reddish tones. They are usually marked with two dark fascia and a small discal spot but these features can be faint or almost absent. The hindwings are lighter buffish brown. The common name derives from the very strong feathering on the antennae of the male. The wingspan is 46-50 mm, the males being usually larger and broader-winged than the females. The females tend to be rather sluggish but the males fly actively at night and are attracted to light. The species is on the wing from September to November.

The larva is brown and twig-like and feeds on a variety of trees and shrubs including birch, blackthorn, elm, hawthorn, oak and sallow. The species overwinters as an egg.

References

• Chinery, Michael Collins Guide to the Insects of Britain and Western Europe 1986 (Reprinted 1991)
• Skinner, Bernard Colour Identification Guide to Moths of the British Isles 1984