Lambdina fervidaria, the curve-lined looper or spring hemlock looper, is a moth of the family Geometridae. It is found in Canada (Nova Scotia, Prince Edward Island, New Brunswick, Quebec, Ontario, Manitoba and Saskatchewan) and the Eastern parts of the United States, south to Georgia. The wingspan is about 27 mm. The moth flies from May to August depending on the location. The larva feed on Quercus and Fraxinus. The subspecies Lambdina fervidaria athasaria prefers Abies balsamea, Picea and Tsuga canadensis