The dynamics of a mass outbreak of the Common pine sawfly near Celle (North Germany) in 1976-1978 is reviewed. The progradation phase was short, with the population increasing rapidly from low levels to critical numbers of about 450 cocoons/m2 on average during the winter 1976/77. This led, within 2 generations, to widespread defoliation. Culmination- and retrograd ation phases commenced in autumn 1977 and were characterized by overpopulation, food shortage, decreasing food quality and mass dying. Furthermore the breakdown of the mass outbreak that followed was partly enduced and accelerated due to the loss of several flight waves of the host, resulting in a substantial prolongation of cocoon diapause. Thereby efficiency of predators, egg- and cocoon parasites increased to such an extent that sawfly populations became drastically decimated. Reproduction; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Land and freshwater zones; Palaearctic region; Europe Tachinidae; Ichneumonidae; Chalcidoidea; Hymenopteran hosts; Diprion pini; Parasitofaunal analysis during mass host outbreak; Germany; North; Celle; Parasitofaunal analysis during mass outbreak of hymenopteran hosts Diprion pini (Diprionidae); Reproductive productivity; Voltinism; Dipteran parasites; Tachinidae; Hymenopteran parasites; Chalcidoidea & Ichneumonidae; Plant hosts; Irruption; Mass outbreak dynamics; Voltinism & parasite load analysis; Germany; North; Celle; Voltinism & parasite load investigations during mass outbreak none2002