none The levels of pupal population belonging to seven species of aphidophagous syrphids, Episyrphus balteatus (de G.), E. alternans (Macq.), Sphaerophoria indiana Big., Metasyrphus (Metasyrphus) confrater (Wied.), M. (M.) latilunulatus (Coll.), Ischiodon scutellaris (Fab.) and Scaeva latimaculata (Brun.) on raya, Brassica juncea Coss. was higher on crop sown very late in November than that in the case of normal and slightly late sowings. In the latter two crops, E. balteatus was the dominant species, whereas I. s. cutellaris was abundant in the very late sown crop. The extent of parasitism among various syrphid species in the three sowings has also been ascertained. Two hymenopterous parasitoids, Diplazon laetatorius Fab. and Diaretus rapae M'Intosh were isolated from aphidophagous syrphid pupae. Animals and man; Control; Biological control; Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Ecology; Community structure; Population dynamics; Land and freshwater zones; Oriental region Syrphidae; Control of; Predator potential; Prey; Aphidoidea (Hemiptera); Predator community dynamics & influences, control significance; Hymenopteran parasites; Diaeretus rapae & Diplazon laetatorius; Prevalence on aphidophagous hosts; Prevalence; Diaeretus & Diplazon (Hymenoptera); Relative abundance; Population size; Aphidophagous community, biological control significance; India; Aphidophage community dynamics & hymenopteran parasite, significance for biological control use Diaeretus rapae (Braconidae ); Diplazon laetatorius (Ichneumonidae ); Dipteran hosts; Syrphidae; Prevalence in host pupae; Prevalence; Syrphidae (Diptera) pupae; India; Prevalence in dipteran host pupae Aphidoidea; Control by; Predator potential; Predators; Syrphidae (Diptera); Predator community dynamics & influences; India; Dipteran predator community dynamics & influences, control significance