Cell c is a small rectangular cell on the anterior margin of the wing between the costa and vein Sc. It is bordered basally by crossvein h. The pterostigma is the somewhat triangular apical part of cell sc, between the apical bend of vein Sc, the costa, and vein R₁. It is often more opaque than surrounding membranous areas of the wing. The length of cell c is measured from the level of crossvein h where it meets the costa to the level of the apex of vein Sc. The length of the pterostigma is measured from the level of the apex of vein Sc to the level of the apex of vein R₁. Their ratio is the length of cell c divided by that of the pterostigma.