In this paper, the selective predation of the female adult spider to both brown planthopper and rice case \orm(Cnaphalocrosis medinalis Guenee) was simulated. The female adult spider shows positive preference to brown planthopper, and negative preference to rice case worm. The female adult also shows positive switching to the second instor nymph of brown planthopper, and negative switching to the bra-chypterous adult. But preference and switching to a certain prey type vary as the relative availability and ...