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Adults are relatively small, 6-9 mm in length (Teskey 1990). The head of the females is grayish pruinose (powdery) with large brown to black glossy areas; the frons is higher than the width at the base; the antennae are slender, with a yellowish scape; the palpi are yellowish brown (Teskey 1990). The thorax is black, with the lateral margin and much of pleura covered with greyish pruinosity and yellow hairs; the legs are variable; the wings are heavily infuscated, with the apical spot broadly united to the crossband (Teskey 1990). The abdomen coloration is also variable, but is usually yellowish orange on the first two tergites, with a lunate (moon-shaped) black spot on tergite 1 meeting a broad black spot on tergite 2; the remaining tergites are darker, sometimes with faint medial triangles (Teskey 1990). The males are similar, but with a more swollen scape, a wider pruinose clypeal stripe, greater pigmentation on wings, and a larger black spot on tergite 2 (Teskey 1990). Due to its size and heavy pigmentation at the wing apex, C. frigidus is not easily confused with any other Chrysops spp. Larvae are cylindrical, elongate, fusiform (spindle-shaped), pale yellow or beige, often with a greenish tinge, 12-15 mm in length. They lack a stigmatal spine, and the length of their respiratory siphon is more than three times longer than the diameter of its base (Teskey 1969).