Botfly

Botflies are a common name for various species of flies in the family Oestridae whose larvae are obligate parasites of mammals. Members of this group are diverse in habitat and host range, from those that infest the nasal passages of livestock to those that develop in the skin or digestive tract of their hosts. Adults resemble other blowflies, but the larval life cycle is the defining feature.

Most botflies have a parasitic larval stage that spends weeks to months inside a vertebrate host, followed by pupation in the soil and emergence as an adult. Dermatobia hominis, the human botfly, is notable: females capture a blood-feeding insect and attach eggs to its body; when the vector bites a host, the warmth triggers hatching and larvae penetrate the skin. Other species deposit larvae directly on the host or in body openings, such as the nasal passages of sheep (Oestrus ovis) or the stomach of horses (Gasterophilus spp.).

Clinical effects vary by species and site but commonly include swelling, pain, itching, and discharge. In livestock, botfly infections can reduce productivity and cause tissue damage; in humans, infections are usually self-limiting but may require removal of the larva. Some infestations can lead to secondary infections or airway or digestive complications if larvae migrate.

Prevention and control focus on fly management and good husbandry. Strategies include regular grooming to remove eggs, insect repellents, manure management, and strategic use of antiparasitic medications under veterinary guidance. Controlling adult flies and interrupting larval development reduces transmission and losses in livestock.