Stylogaster eggs on blow flies attracted to millipede defence secretions in Tanzania, with a stab at summarising their biology (Diptera: Conopidae & Calliphoridae)

The genus Stylogaster Macquart (Diptera: Conopidae) is sister to the remainder of the Conopidae. While all other Conopidae are endoparasitoids of aculeate Hymenoptera, species of Stylogaster appear to be endoparasitoids of ‘orthopteroids’, as the only confirmed rearing records are from crickets and cockroaches. Many calyptrate flies have been observed with Stylogaster eggs attached, but since no Stylogaster have been reared from any dipterans, it is still unknown if these flies are hosts, results of accidental oviposition or carry the eggs to the actual hosts. In this study, we report our findings of Stylogaster eggs on blow flies (Calliphoridae) attracted to millipede defence secretions in Tanzania. Out of seven different species collected and a total of 301 specimens, only flies of the genus Tricyclea Wulp had Stylogaster eggs attached. Out of 133 Tricyclea collected, 32 (24%) had Stylogaster eggs attached and, with one exception, all eggs were attached to the abdomen. The lifecycle of Stylogaster is summarised and discussed with a particular focus on dipteran egg-carriers.