Colostygia multistrigaria, the mottled grey, is a species of moth in the family Geometridae. It is found in western and south-western Europe and North Africa. The habitat is damp woodlands, heaths, and mosses.
The wingspan is 26–. The ground colour is grey mottled with brown. The forewings have a weak darker central band. The basal patch, central band, and shade before the whitish submarginal line are also sometimes darker. The hindwings are pale whitish grey.
The caterpillar is ochreous grey, with three brownish lines along the back, and two other lines on each side, the upper one yellowish, wavy, and edged above with dusky. The larva is uniformly cylindrical, brown-grey, tinged with green dorsally, rather paler ventrally. There is a blackish dorsalline, at least on the last few segments. The spiracles are minute, blackish. The pupa is dark reddish, dorsally and anally more black.[1] Adults are on wing from March to April[2] in one generation per year.
The larvae feed on Galium species.[3] Larvae can be found from March to June. The species overwinters in the pupal stage.[4] About dusk the moths may be seen on the lower parts of fences, tree-trunks, rocks, sitting on grass and other vegetation.