Platystomatidae

This is an adult male Bromophila caffra (Macquart, 1846). Adults are slow ponderous flies and their black & red colouration suggests  perhaps a toxic message in defense of their unwillingness to fly. Knowledge of larval habits is very rudimentary. There appears to be an association with the roots of Terminalia trees (Combretaceae), from which the larvae sequester various toxic compounds (probably cyclic triterpenes) possibly for defense. This may render the adults toxic too, as a defense against predation – not a thoroughly tested hypothesis. The adults range greatly in size - this specimen was a whopping 25mm, other males I have examined are as small as 12mm, and females range from 9mm to 22mm; wing spans up to 48mm have been recorded. Size of adult fly is generally defined by the amount and quality of food resources available during the larval stages.