A pterostigma, or wing mark, is not present in either sex, but the females have denser veining that simulates a wing mark. It is called ‘false wing mark’.
The wing mark, or pterostigma, on a damselfly wing serves multiple purposes. It acts as a weight, helping to stabilize the wing during flight and reduce vibrations. Additionally, the pterostigma can be used for sexual signaling and species recognition, as it often differs in size and color between species and sexes.