Two species of Neoseiulus, N. californicus and N. cucumeris, showed potential for biocontrol of phytophagous mites on strawberry. N. californicus controlled Tetranychus urticae on potted strawberry plants in a gauze-sided glasshouse at temperatures comparable to early summer in the UK (8-20 degrees C). Both species of phytoseiid reduced numbers of the tarsonemid Phytonemus pallidus on potted strawberry plants under glasshouse conditions (15-23 degrees C). In several experiments reductions in the range of 71-81% in numbers of tarsonemid active stages and eggs, compared to non-release plants, were obtained. The importance of establishing a suitable predator: prey ratio at an early stage was demonstrated in an experiment where an initial ratio of 1 N. cucumeris: 10 P. pallidus gave a greater degree of control than 1:20 or 1:40.