Zygopteran wing display is reviewed, and a distinction is made between threat display of the male and refusal display of the female. The former is suggested to have originated from preliminary movements of attack flight, while the latter from preliminary movements of escape flight. The resemblance of the displays in the 2 sexes is discussed in terms of imitation of the male by the female, through advergent evolution, according to a mimicry system in which the male acts as the model, the female as the mimic, and the approaching male as the signal receiver, which responds the same way to both model and mimic signals.