The family Mormotomyiidae (Diptera: Ephydroidea) contains only one known species, Mormotomyia hirsuta, commonly known as the frightful hairy fly, which is found in Kenya. The fly was first described by English entomologist Ernest Edward Austen, and specimens have been collected from one location on a mountain in the Ukasi Hill (Okazzi Hills), in a cleft where a bat roost is located; this may possibly be the most restricted geographic distribution for any fly family. The larvae have been collected from batguano. Adult flies are believed to feed on bodily secretions of bats. The fly measures about 1 cm long, with hairy legs, and, due to its non-functional wings and tiny eyes, looks more like a spider than a fly. Specimens have been collected only three times, in 1933, 1948, and 2010. Tested members of the population showed higher levels of genetic variation than would be expected for such a restricted range, suggesting that there are additional undiscovered populations and that there is gene flow between them and the known population in Ukasi Hill.
^Kirk-Spriggs, A.H., Kotrba, M. & Copeland, R.S. 2011. Further details of the morphology of the enigmatic African fly Mormotomyia hirsuta Austen (Diptera: Mormotomyiidae). African Invertebrates52 (1): 145-165.PDF
^Austen, E.E. 1936. A remarkable semi-apterous fly (Diptera) found in a cave in East Africa, and representing a new family, genus, and species. Proceedings of the Zoological Society of London (1936): 425–431.
^Copeland, R.S., Kirk-Spriggs, A.H., Muteti, S., Booth, W. & Wiegmann, B.M. 2011. Rediscovery of the "terrible hairy fly", Mormotomyia hirsuta Austen (Diptera: Mormotomyiidae), in eastern Kenya, with notes on biology, natural history, and genetic variation of the Ukasi Hill population. African Invertebrates52 (2): 363-390.