none There was a range of severity of parasitism of stem-borer larvae by Hymenoptera and Nematoda and much premature death of the larvae. A nematode, Panagrolaimus rigidus , normally considered to be saprophytic, was implicated in some mortality of stem-borer larvae. Parasites diseases and disorders; Parasites; Helminth parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Ecology; Population dynamics; Land and freshwater zones; Palaearctic region; Europe; United Kingdom Mermithidae; Panagrolaimus rigidus (Nematoda ); Chasmodon apterus (Braconidae ); Dipteran hosts; Oscinella; Prevalence & effect on host mortality; Prevalence; Levels in Oscinella (Diptera) & effect on host mortality; England; Cumbria; Prevalence in dipteran host & effect on host mortality Oscinella (Chloropidae); Nematode parasites; Mermithidae & Panagrolaimus rigidus; Hymenopteran parasites; Chasmodon apterus; Prevalence & effect on mortality; Prevalence; Hymenopteran & nematode parasites; Mortality; Hymenopteran & nematode parasite effects; England; Cumbria; Hymenoptera & nematode parasite prevalence & effect on mortality