The feathered thorn (Colotois pennaria) is a moth of the family Geometridae.

They are usually marked with two dark fascia and a small discal spot but these features can be faint or almost absent.

Prout describes the aberrations[1][2] The females tend to be rather sluggish but the males fly actively at night and are attracted to light.

The egg is olive-green with a ring of pale specks round the micropylar end; laid in a cluster on a twig, hibernating.The caterpillar is hairless, brown or purplish grey with ochreous spots and purplish grey with ochreous spots with reddish anal points.It is twig-like and reaches a length of up to 50 mm.

It can be found from May to July feeding mainly at night on a variety of trees and shrubs (see list below).