Flies are ubiquitous insects, recognized by their ability to fly. They belong to the order Diptera, a name derived from Greek words meaning “two wings,” which accurately describes their primary characteristic: a single pair of functional forewings. Their hindwings are modified into small, club-shaped halteres, which act as gyroscopic balancing organs during flight, allowing remarkable aerial maneuverability. While flight defines most flies, some species do not possess or retain wings, leading to variations within this diverse insect group.
The Name for a Wingless Fly
The scientific term for an insect that naturally lacks wings is “apterous,” which also applies to flies. The word “apterous” originates from Greek, where “a-” means “without” and “pteron” refers to “wing.”
This term describes the physical condition of lacking wings and is used across entomology for any insect group that has evolved to be wingless. It does not denote a specific species but rather a characteristic that can arise in various insect lineages. The term highlights a significant departure from the typical winged form associated with most adult insects.
Flies Naturally Lacking Wings
Some fly species have naturally evolved to be wingless or have significantly reduced wings, adapting to specific environments or lifestyles. This evolutionary loss of wings can offer several advantages. For instance, in windy environments like islands or high-altitude regions, being wingless prevents individuals from being blown away, conserving energy that would otherwise be spent on flight or fighting strong gusts.
Many naturally wingless flies are parasites, where wings would be a hindrance rather than a benefit. Examples include certain bat flies (families Nycteribiidae and Streblidae), which are ectoparasites that spend their lives clinging to the fur of bats. These flies often have flattened bodies and strong legs adapted for navigating through their host’s fur, making wings unnecessary and potentially cumbersome. The sheep ked, Melophagus ovinus, is another well-known example; this wingless, tick-like fly lives its entire life cycle within the wool of sheep, feeding on their blood.
How Flies Can Otherwise Be Wingless
Beyond natural evolution, flies can become wingless through other mechanisms. Genetic mutations can lead to winglessness in individual flies within species that are typically winged. For example, in the common fruit fly, Drosophila melanogaster, specific genetic defects, such as mutations in the “vestigial” gene, can result in individuals being born with greatly reduced or absent wings, making them unable to fly. These mutations are frequently studied in laboratory settings to understand wing development.
Developmental issues during a fly’s early life stages can also interfere with proper wing formation. Environmental stressors like extreme temperatures or nutritional deficiencies during the larval or pupal stages can disrupt the complex processes of metamorphosis, leading to an adult fly emerging with malformed or incomplete wings.
Physical damage is also a common cause of wing loss in adult flies. Wings are delicate structures and can be torn or broken due to collisions with objects, entanglement in spiderwebs, or attacks from predators. Once an adult fly’s wings are damaged or lost, they cannot regrow, as insects acquire their wings during their final molt and lack the ability to regenerate them later in life.
Human intervention also contributes to the presence of wingless flies. Scientists may intentionally breed or genetically engineer flies to be wingless for research purposes, such as studying genetics, development, or neurological diseases. These laboratory-reared wingless flies are also used as convenient feeder insects for small captive animals, providing a protein source that cannot escape.