Temperature preference and effects of photoperiod on oviposition behavior of five species of pteromalid wasps were investigated using house fly pupae,Musca domesticaL.. as hosts. All five species were exposed to treatments (temperature and photoperiod) for 24 h and then held at 25°C for progeny development. Mean parasitoid emergence for the five species in descending order wasMuscidifurax raptorGirault&Saunders (46%).Pachycrepoideus vindemiaeRondani (37%),M. zaraptorKogan&Legner (26%),Urolepis rufipesAshmead (14%). andSpalangia nigroaeneaCurtis (<1%). Length of photophase (6, 12, or 18 h) did not significantly effect parasitoid emergence for any species. Temperature, however, had a significant effect on oviposition behavior, and the five species appeared to respond differently to the different temperature levels (20, 25, and 30°c). Temperature had a significant quadratic effect on oviposition behavior ofM. raptor,P. vindemiae, andU. rufipes. Emergence levels ofM. raptorwere highest from hosts held at 25 and 30°c. Emergence ofP. vindemiaeandU. rufipeswas highest from hosts held at 25°C. Temperature had a significant linear effect on the oviposition behavior ofM. zaraptor; highest emergence occurred from hosts held at 30°C. Emergence levels forS. nigroaeneawere too low to make comparisons between treatments. Effects on fly eclosion, sex ratios, and parasitoid-induced mortality for the five species are reported along with possible reasons for lowS. nigroaeneaemergence.