Fossil Fly in Baltic amber for sale. Empididae is a family of flies with over 3000 described species. Three subfamilies are sometimes regarded as separate families: Atelestidae, Hybotidae and Microphoridae. Empidids are mainly predatory flies and exhibit a wide range of forms but are generally small to medium sized, non-metallic and rather bristly. Common names for members of this family include dance flies (referring to the habit of some species to form large dancing swarms), dagger flies (referring to the sharp piercing mouthparts of some species) and balloon flies. Distribution is worldwide but the majority are found in northern temperate areas.Some empidids such as the European species Hilara maura have an elaborate courtship ritual in which the male wraps a prey item in silk and presents it to the female to stimulate copulation. Empidid larvae are also largely predatory (although some are scavengers) and occupy a wide range of habitats, both aquatic and terrestrial. Empidids are well represented in amber deposits and the family certainly seems to have been well established by the Cretaceous period at the latest.