The porcelain gray is one of several species of geometrid moths called “grays,” for their overall color. This moth is widespread in eastern North America. Its larva, called the dash-lined looper, eats leaves from a wide variety of evergreens and other trees.
The overall background color of the wings is indeed usually gray or whitish, but individuals may appear lighter or darker, and more or less tan or brownish. The intensity of the markings varies, as well. The wings are sprinkled with tiny brown specks. A number of dark brown and gray lines cross the wings, curved similar to the outer margin of the wings. At least one of these curved lines has a toothed margin, with each small triangular “tooth” pointing toward the outer edge of the wing. Several other key markings (dark spots on the leading edge of the forewing and positioning of other spots) are beyond the generalized scope of this introductory field guide page.
The slender caterpillars are excellent twig mimics! Called dash-lined loopers, they are blotchy gray, tan, and brown (sometimes greenish) with numerous wrinkles, bumps, and dots that make them look exactly like a small twig. They habitually rest at about a 45-degree angle to a surface, holding their bodies completely straight and still, which enhances their camouflage. When they move, they “walk” in inchworm fashion. They are slightly less than 1 inch long.
To learn more about geometrid moths as a group, visit their family page.
Similar species: The porcelain gray is confusingly similar to many, many grayish-brown, mottled geometrid moths (a family of moths that have slender bodies, rest with their wings held flat out to the sides, and have markings that continue uninterrupted across all four wings). These bark-camouflaged moths have a demure beauty that begs close observers to dive deep and learn their official names. We hope you feel empowered to pursue the names of the moths you discover. But even if you only get to the point where you think, “this has to be some kind of geometrid moth,” you’re doing great!
Wingspan: about 1¼ inches.
Statewide.
Habitat and Conservation
Like other moths, this species is most likely to be found in places where its host plants are abundant. In Missouri, red cedar is abundant nearly everywhere, so this moth may be seen almost anywhere.
Like most other moths, the porcelain gray is attracted to lights at night. In the mornings, look around where lights had shone all night, and see what kinds of moths are resting nearby.
Food
The caterpillars can feed on the foliage of a variety of host plants, which helps explain their wide distribution across eastern North America. In Missouri, their most widespread host plants are eastern red cedar and various species of pines and other conifers (many of which are cultivated); they also reportedly feed on sugar maple, soapberry, birches, elms, oaks, and poplars.
Elsewhere, they eat firs, spruces, hemlocks, tamarack/larch, and various types of cedars.
Status
Common breeding resident with one or two broods per year.
Life Cycle
Adult porcelain grays are present from spring into autumn. There may be one or two generations (broods) per year. Females deposit eggs on the leaves of suitable host trees in midsummer. This species overwinters in its next-to-last caterpillar stage; when warm temperatures return in spring, the larvae become active, feed on the tender new springtime leaves, and pupate in May or June.
Human Connections
People who enjoy looking at (and photographing) moths rig up white bedsheets, illuminated by bright lights, at night to attract a variety of moths and other cool night-flying insects. It’s fun to discover new species, and meeting the challenge of identifying them is a satisfying hobby.
Ecosystem Connections
The stock-still positions, and the drab yet intricate designs on both adults and caterpillars, camouflage them when they rest on tree trunks and branches. Camouflage is a reminder that these insects are preyed upon by visual predators such as birds. If a hunting bird doesn’t notice the moth, the moth may survive and reproduce. Insect-eating birds, meanwhile, have developed the habits of hopping busily on tree trunks and branches, fluttering, pecking, and probing — behaviors that may cause the moth or caterpillar to flinch or flush, revealing its presence to the predator.
