Dead-end parasitism of bombyliid larvae in tabanid adults

During examination of adult tabanids for the parasitic larvae of miltogrammine sarcophagids (Macronychia sp.), the larvae of a brachycerous dipteran, believed to be a bombyliid, were also discovered in the same host species (Hybomitra lasiophthavae (Macq.)). Of 871 females taken in Manitoba traps baited with carbon dioxide on the Navasota River in south-central Texas from 1 April to 9 May, 3.8% were infested with 1-7 larvae per host (averaging 1.4). Most (91.3%) of the 46 infesting larvae were removed from the abdomen where they were found free near the terminal segments. Their size and encapsulation suggested that the larvae died soon after penetration of the host. However, the host-parasite relationship is significant because it demonstrates the apparent attractiveness and susceptibility of tabanids as hosts to parasitic insects.