Brachyptery
Brachyptery is an anatomical condition in which an animal has very reduced wings. Such animals or their wings may be described as "brachypterous". Brachypterous wings generally are not functional as organs of flight and often seem to be totally functionless and vestigial. In some species however, wings that are vestigial in the sense of not retaining any function related to flight, may have other functions, such as organs of aposematic display in some Orthoptera and Phasmatodea. Brachyptery occurs commonly among insects. An insect species might evolve towards brachyptery in reducing its flight muscles with their associated energy demands, or in avoiding the hazards of flight in windy conditions on oceanic islands, in which flying insects are prone to drowning. Brachyptery also is common in ectoparasitic insects that have no use for wings, and inquiline insects with socially parasitic life strategies that do not require functional wings.
In some species of insects brachyptery occurs in some members (say in only one gender, or only some castes), whereas fully functional wings occur in macropterous individuals. Other forms of brachyptery may depend on the temperature at which the insect grew and developed. In winter for example, some species grow reduced wings, whereas in summer they grow fully developed wings that are adequate for migration.
The extreme form of brachyptery, in which no wings grow at all, such as in fleas or worker Ants is called aptery.