The Bombyliidae (bee flies) are one of the largest families of Diptera, with over 5,000 valid species described worldwide. Their high diversity may be due to the parasitoid habit of the majority of their larvae (Du Merle, 1975; Price, 1980; Yeates and Greathead 1996). Adults feed on nectar and pollen, and no doubt feature prominently in angiosperm pollination syndromes (Armstrong, 1979; Grimaldi, 1988; Heard et al., 1990), although few species have been studied in detail. Bee flies occur on all continents except Antarctica, however their highest diversities occur in semi-arid and arid environments (Hull, 1973).

The family includes a wide variety of morphological forms, such as the enormous Palirika marginicollis (Gray), with irridescent green-blue body scales recalling those found on the wings of a Morpho butterfly, and striking black and hyaline wings spanning 45 mm; and the tiny, delicate, humpbacked yellow and black species of Glabellula Bezzi with hyaline wings and a body length about 1 mm.

This structural diversity is reflected in the higher classification of the family, with a total of 31 subfamilies proposed to date. Up until recently the subfamilies of Bombyliidae were based on classifications formulated early this century, and those divisions did not accurately reflect the cladistic relationships within the family. The subfamilies were divided further into tribes by Hull (1973).

Numerical cladistic analyses of particular subgroups of Bombyliidae have appeared only in the last few years (Evenhuis, 1990, 1993; Yeates, 1988, 1989, 1990, 1991a, b; 1994, Yeates and Lambkin 1998, Lambkin et al. 2003). The family was catalogued by Evenhuis and Greathead (1999).

Yeates (1992) affirmed Theodore's (1983) suggestion that Prorates Melander showed affinities with the window flies, and moved the entire Proratinae except Apystomyia Melander, to the Scenopinidae, forming the two most plesiomorphic subfamilies, the Caenotinae and Proratinae. Yeates (1994) placed Apystomyia in the Hilarimorphidae, as the sister family to the Bombyliidae. With the Proratinae removed, the Bombyliidae are a much more homogenous group, however their monophyly remains weakly supported at present.