Immature stages of two Australian mydas flies (Diptera: Mydidae) of the genera Diochlistus and Miltinus

The Mydidae are a small family (~470 described species) of medium to large‐bodied flies belonging to the Asiloidea and are closely related to the Asilidae and Apioceridae. The biology of mydas flies, as they are commonly known, is poorly known globally, with the larva and pupa of only one American species described a century ago. Field work over the past few years in south‐eastern Australia has uncovered the life histories of two Australian species belonging to different subfamilies: Diochlistus gracilis (Macquart 1847) (Diochlistinae) and Miltinus viduatus (Westwood 1835) (Apiophorinae). Here, we present detailed descriptions and illustration of the larvae and pupae of these species and compare them with Mydas clavatus Drury (Mydinae) from North America. We also present some observations on the mating behaviour of D .  gracilis . The relationships of the 10 Mydidae subfamilies, based exclusively on characters of the adult stage, are poorly resolved. The differences between the larvae and pupae of these two Australian genera provides evidence that there may be phylogenetically informative variation in the immature stages that could be used in future comprehensive studies on the relationships of mydas flies. These descriptions of mature larvae represent the second and third species to be published worldwide.