Periodic exposure of laboratory-rearedMusca domesticaL. pupae was used to study seasonal and diel activity patterns of pteromalid pupal parasites in poultry manure.Muscidifurax zaraptorKogan&Legner (July to October),M. raptor(Girault&Sanders (June to October), andSpalangia cameroniPerkins (May to November) were most commonly collected. Others includedS. nigroaeneaCurtis (July, September, November),S. endiusWalker (July), andNasonia vitripennis(Walker) (March, July). Exposure of pupae during a 12-h daytime or 12-h nighttime period indicated thatM. zaraptorand probablyS. cameroniwere primarily diurnal in their searching activity. Some nocturnal activity was noted forS. cameroni. Predation of pupae bySolenopsis maniosaWheeler appeared to be severe in peripheral surface manure areas during the summer. A treatment of extensive wet manure areas with dimethoate larvicide appeared to have a deleterious impact on parasite activity, particularlyM. zaraptorandM. raptor, in the summer of 1984.