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A relatively large geometrid, with striking white and light grey forewing pattern. Median band with sinuate borders and a large white discal spot, light grey wing margin with a white subterminal line, wing fringe checkered black and white. Hindwing white with a loose band of median and subterminal speckling, more pronounced on the underside. Females slightly smaller. The Sagebrush Girdle is similar to Caripeta species, but none of the Caripeta are pale silver-grey and white like trilinearia, and inhabit conifer forests rather than sagebrush grasslands.

This graceful moth is one the few geometrids which are restricted to prairie habitats; the pale silver-grey colouration matches that of its surroundings of sagebrush and prairie. Except for the egg, the immature stages are undescribed (McGuffin 1987).