A semi-defined synthetic diet for Glossina spp. was developed and used successfully to rear G. palpalis palpalis (Robineau-Desvoidy) for five generations. The survival, fecundity and offspring size achieved were similar to those obtained when flies are fed on whole blood in vitro. The diet was also tested on G. morsitans morsitans Westwood, G. austeni Newstead and Stomoxys calcitrans (L.), and in all cases was satisfactory. The diet consists of commercially available ingredients and is the first such diet to be developed for obligate haematophagous insects.