Brachyptery

Brachypterous wings generally are not functional as organs of flight and often seem to be totally functionless and vestigial.

In some species, however, flightless wings may have other functions, such as aposematic display in some Orthoptera and Phasmatodea.

An insect species might evolve towards brachyptery by reducing its flight muscles and their associated energy demands, or by avoiding the hazards of flight in windy conditions on oceanic islands, in which flying insects are prone to drowning.

This may be to free energy for reproduction, or may be because some insect males (such as cockroaches) use their wings in courtship displays.

[4] Some animals, like fleas and worker ants, display an extreme form of brachyptery called aptery, in which no wings grow at all.