We investigated the overwintering sites of the predacious mite Neoseiulus californicus in two satsuma mandarin orchards on Jeju Island, Korea, in February 2008. Our objectives were to improve the biological control strategy with N. californicus in perennial crops and to develop effective methods for examining the overwintering situations of N. californicus in the field. Nearly all specimens of N. californicus collected in the orchards were adult females, and the numbers of adult males and juveniles were very low. Most N. californicus were collected on herbaceous plants on the ground rather than on satsuma mandarin trees or woody plants surrounding the orchards. Among herbaceous plant species, higher densities of N. californicus were consistently found on species with rosette-type leaves compared to those with non-rosette-type leaves. Our results suggest that rosette-forming herbaceous plants are effective overwintering sites for conserving N. californicus in orchards. Furthermore, these plants would also provide useful sites for examining the potential overwintering situations of N. californicus in the field.