In 1993–1995 from the cabbage aphid colonies, fed on nine different varieties of Brassica oleracea L. syrphid larvae and pupae were collected. The remaining emerged adults of Syrphidae were classified to eight species. The parasitization varied within the years of observation and oscillated from 14,4% to 46,4%. Four parasitic Hymenoptera: Diplazon laetatorius (F.), Diplazon sp., Pachyneuron grande (Thoms.), and Syrphophagus aeruginosus (Dalm.) were reared. The parasitoids identified belong to the following three families Ichneumonidae, Pteromalidae, and Encyrtidae. The largest group of reared parasitoids belonged to the family Ichneumonidae of which the most frequent was Diplazon laetatorius (F.). It occurred in each year of observations. The parasitization by D. laetatorius reached 21,7%.
In 1993–1997, 990 pupae of diamondback moth (Plutella xylostella L.) were collected from nine different varieties of Brasica oleracea L., grown on experimental farm near Kraków. Only 234 moths (23.6%) were recovered from the cocoons. The most important factor reducing the population of DBM was parasitization (65.1%). It varied between the years of observation and oscillated from 60% to 90.3%. Sixhundred and fourty four specimens of parasitic wasps belonging to 11 species from families: Ichneumonidae (5 species), Braconidae (3 species), Pteromalidae (2 species) and Eulophidae (1 species) were reared out. In each year of observations the most abundant species among DBM parasitoids was Diadegma fenestralis Holmgr. as it constituted 71.4% of all of the wasps reared. In the years 1994 and 1996 with low abundance of diamondback moth, D. fenestralis was the only species parasitizing 66.7% and 89.5% of the pest larvae.