none Geomyza tripunctata; FARMING-AND-AGRICULTURE; GRASSLAND-; CULTIVATED-LAND-HABITAT; Ploughing; ENGLAND-; West Yorkshire; Grassland ploughing, effect on hymenopteran parasite survival Geomyza tripunctatus; HYMENOPTERAN-PARASITES; Chasmodon apterus; Parasite survival, effect of grassland ploughing, England Oscinella; FARMING-AND-AGRICULTURE; HYMENOPTERAN-PARASITES; Chasmodon apterus; Parasite survival, effect of grassland ploughing; GRASSLAND-; CULTIVATED-LAND-HABITAT; Ploughing; ENGLAND-; West Yorkshire; Grassland ploughing, effect on hymenopteran parasite survival Chasmodon apterus; FARMING-AND-AGRICULTURE; Ploughing; DIPTERAN-HOSTS; Geomyza tripunctata & Oscinella; Parasite survival; SURVIVAL-; Ploughing effect; GRASSLAND-; Ploughing effect on survival; CULTIVATED-LAND-HABITAT; Grassland ploughing, effect on survival; ENGLAND-; West Yorkshire; Effect of grassland ploughing Chasmodon apterus Nees is a ground-dwelling and important parasitoid of the frit fly in grassland. In 1985 and 1986, the new grass in the ploughed areas had more frit fly larvae and immature parasitoids than the unploughed permanent pasture grass. In 1985, the adults of C. apterus survived ploughing and other soil cultivation probably due to the single ploughing of that year. In 1986, double-ploughing appeared to have reduced the number of C. apterus. It is therefore advised that methods which involve little or no soil cultivation should be utilized in sward improvement techniques.