none. Observations on parasitism of eggsacs of the linyphiid spiders Erigone spp., Oedothorax spp., Bathyphantes gracilis and Lepthyphantes tenuis by four species of hymenopterous parasitoids in a field of winter wheat are described. The dominant parasitoids emerging from eggsacs were Gelis festinans (Ichneumonidae) and Baeus sp. (Scelionidae). Percentage parasitism of introduced and naturally occurring eggsacs was compared for the months of May, June and July. No eggsacs of Oedothorax spp. and B. gracilis were parasitized. Oedothorax spp. females were observed, in both laboratory and field, to guard their eggsacs efficiently against attack by parasitoids. The percentage of naturally occurring eggsacs of Erigone spp. parasitized by G. festinans was not significantly different from the percentage parasitism of eggsacs introduced into the field in modified Petri dishes; the Petri dish introduction method therefore provides a simple and efficient means of assessing parasitism in the field. ENGLAND-; West Sussex, Littlehampton.