Brachyptery is an anatomical condition in which an animal has very reduced wings. Such animals or their wings may be described as "brachypterous". Another descriptor for very small wings is microptery 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 sex, or only some castes), whereas fully functional wings occur in macropterous individuals. Often when brachyptery is sex-specific, females are the sex with reduced wings, including reduced wing musculature. This may be to free energy for reproduction, or may be because some insects (such as cockroaches) males use their wings in courtship displays. Other forms of brachyptery may depend on the temperature at which the insect grew and developed. In winter for example, some species of aphids grow reduced wings, whereas in summer they grow fully developed wings.  The extreme form of brachyptery, in which no wings grow at all, such as in fleas or worker ants is called aptery.
- Young, Chen; Yang, Ding (April 2002). "Notes on Female Brachyptery in Nephrotoma basiflava Yang and Yang (Diptera: Tipulidae)". Journal of the Kansas Entomological Society. 75 (2). Retrieved 28 November 2020.
- Kotyk, Michael; Varadínová, Zuzana. "Wing reduction influences male mating success but not female fitness in cockroaches". Scientific Reports. PMID 28539621.
- Bale, Jefferey (1999). "Impacts of Climate Warming on Arctic Aphids: A Comparative Analysis". Ecological Bulletins. 47 (Responses to Global Change in the North). Retrieved 28 November 2020.