Despite knowledge of parasite biology being essential for host-parasite system functioning to be understood, the life histories of many parasites remain little studied. One example being the hippoboscid Crataerina pallida (Olivier in Latreille, 1812) (Diptera: Hippoboscidae), a nest ectoparasite of the common swift, Apus apus L. (Aves: Apodidae). The factors influencing adult parasite emergence remain unclear. Whether temperature affects emergence was studied by exposing overwintering pupae to differing temperature regimes. At higher temperatures, greater numbers of adults emerged. This indicates that adult hatching is temperature mediated and may be enhanced by host presence. The relationship between C. pallida and their hosts is thus close.