The phlebotomine sand flies—Phlebotomus spp (Old World sand flies) and Lutzomyia spp (New World sand flies)—are members of the family Psychodidae. These flies are confined primarily to the tropical and subtropical regions of the world.
Members of these genera are tiny, mothlike flies, approximately 1.5–4 mm long. The legs are as long as the antennae, comprising 16 segments that often have a beaded, hairy appearance. They are commonly known as sand flies, moth flies, or owl midges. The key morphological feature for identification is that the body of the sand fly is covered with fine hairs. (See .)
Sand fly (Phlebotominae subfamily). Scale bar = 1 mm.
Courtesy of ABOL/HP Fuehrer Vetmeduni Vienna.
Female sand flies have piercing mouthparts and feed on the blood of a variety of warm-blooded animals, including humans. Many species feed on reptiles. Male sand flies suck moisture from any available source and are even said to suck perspiration from humans.
Sand flies tend to be active only at night and are weak fliers; their flying is deterred by air currents, even slight ones. During the day, sand flies seek protection in crevices, caves, stone walls, vegetation, and dark buildings. They often seek protection within rodent and armadillo burrows; these mammals can serve as reservoir hosts for Leishmania spp.
Sand flies breed in dark, humid environments that have a supply of organic matter to serve as food for the larvae. They do not breed in aquatic environments.
Pathology of Sand Flies
Sand flies are tiny flies that serve as a vector and definitive host for Leishmania spp, zoonotic protozoan parasites that infect the reticuloendothelial cells of capillaries, the spleen, and other organs in humans, dogs, cats, horses, and sheep.
Diagnosis of Sand Flies
Like black flies, sand flies can most often be collected in the field and are not found on animals. They can be identified by their small size and hairy wings and bodies. Identification of genus and species is complex and best left to an entomologist.
Treatment and Control of Sand Flies
Destruction of habitat and indoor spraying of insecticides with residual activity
Deltamethrin-impregnated dog collars
Insecticide spraying of larval habitat is usually not possible because of the difficulty of accessing breeding sites. Removing dense vegetation can discourage breeding. Spraying residual insecticides on surfaces in and around homes remains an important control measure; however, its effectiveness is limited for sand fly species that feed away from human dwellings.
In general, populations of sand flies have decreased as a collateral result of intense mosquito control programs. In situations where dogs are the principal blood source for sand flies and act as important reservoirs of Leishmania spp, deltamethrin-impregnated dog collars have demonstrated effectiveness in decreasing sand fly feeding on dogs and lowering transmission risk (1). Similarly, permethrin-based topical products can protect individual dogs from sand fly bites.
Effective tools for decreasing canine exposure to sand flies are available. The challenge is sustaining implementation of proven measures, including high collar coverage in dog populations, timely replacement of collars, owner compliance, and integration of dog protection strategies into leishmaniasis control programs. Implementation-focused approaches are likely to provide the most economical and environmentally sustainable means of decreasing the transmission and spread of Leishmania spp.
For More Information
Repellents: protection against mosquitoes, ticks and other arthropods. EPA.
Also see pet owner content regarding flies and mosquitoes of dogs, cats, and horses.
References
Coura-Vital W, Leal GGA, Marques LA, Pinheiro ADC, Carneiro M, Reis AB. Effectiveness of deltamethrin-impregnated dog collars on the incidence of canine infection by Leishmania infantum: a large scale intervention study in an endemic area in Brazil. PLoS One. 2018;13(12):e0208613. doi:10.1371/journal.pone.0208613
