Colotois pennaria

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Geometridae
Genus: Colotois
Species: C. pennaria
Common name: Feathered Thorn.
Wingspan: 46–50 mm.

Forewings are orange-brown to reddish-brown with darker cross-lines and variable shading; hindwings are paler with similar cross-lines. Males have strongly bipectinate (feather-like) antennae, hence the name “feathered thorn”, the females have thinner, less feathery antennae. This species flies in autumn, usually from September to November in Europe, depending on the region. The caterpillars are long, slender, and twig-like in appearance, grey-brown with mottling, allowing excellent camouflage among twigs and branches. They feed on a wide range of deciduous trees and shrubs, including oak (Quercus), birch (Betula), willow (Salix), and hawthorn (Crataegus). The adults emerge in autumn and are active at night. The females lay eggs on host plants which overwinter and hatch in spring, and the caterpillars feed through spring and summer before pupating in soil or leaf litter.