warbleys

Warbleys are a type of parasitic fly that belong to the family Hippoboscidae, commonly found in birds, particularly those in the order Passeriformes, such as sparrows, finches, and warblers. These flies are obligate parasites, meaning they rely entirely on their host for survival, feeding on their blood. Warbleys are small, wingless insects, typically measuring around 3–5 millimeters in length, with a flattened, oval-shaped body that allows them to cling tightly to feathers.

The life cycle of warbleys is closely tied to their avian hosts. Adult flies attach themselves to the host’s plumage, where they feed on blood and lay eggs. The eggs hatch into larvae, which then drop to the ground, pupate, and eventually emerge as adult flies. Unlike some other parasitic flies, warbleys do not burrow into the host’s skin but instead remain on the surface, feeding intermittently. While their presence can be irritating to birds, they generally do not cause severe harm, though heavy infestations may weaken the host.

Warbleys are found worldwide, with different species adapted to specific bird species and regions. They are often studied in the context of avian ecology and parasitology to understand host-parasite relationships. Unlike true warbles (such as those caused by bot flies), which burrow into the host’s flesh, warbleys remain external, making them less harmful but still significant in the study of bird health and behavior. Their unique adaptations, such as winglessness and a flattened body, reflect their specialized lifestyle as permanent ectoparasites.