The predatory mite, Neoseiulus barkeri (Hughes), is a generalist mainly preying on spider mites and thrips. This mite iswidely used as a biocontrol agent due to its wide range of prey, strong predatory ability and ease of artificial rearing.

In this paper, the foraging ability of N. barkeri with regard to spider mites Tetranychus truncatus, Western flower thrips

Frankliniella occidentalis（Pergande) and a combination of these prey species was investigated by a series of release

recapture experiments in a greenhouse. There were three treatments: (1) infested plants with spider mites vs clean plants;

(2) infested plants with thrips vs clean plants; (3) infested plants with spider mites and thrips vs clean plants. Whenreleased inside a hexagon in which the six apices were occupied by cucumber plants that were alternately clean or infestedwith spider mites, thrips, or mixed prey, the fraction of predators on plants in each treatment stabilized with time within

1 day to levels 6525%±161%, 6275%±131% and 8175%±214%, respectively. Moreover, significantly more predatory

mites were recaptured on infested than on clean plants; 535%±56%、495%±36% and 74%±27% of all released N.

barkeri were found on the three kinds of infected plants, respectively. This suggests that N. barkeri could accurately

locate infested plants, irrespective of whether they were infested with T. truncatus, F. occidentalis or both prey species.

The potential for using this predator to control spider mites and thrips in greenhouses is discussed.