A recent investigation revealed that Neoseiulus californicus is the dominant species among the natural enemies of citrus red mite Panonychus citri at the mandarin orange orchards in central Japan. However, the population of citrus red mite reaches a peak of more than 10 female adults per leaf for a short period in July because the N. californicus population increase occurs several weeks after the increase of spider mites. One of the reasons for this is assumed to be fewer habitats of phytoseiids by the herbicide spraying throughout the year. We then compared the occurrence of N. californicus in orchards covered with Poaceae plant, Festuca myuros to that in clean cultivations in 2004. In the sod cultures, N. californicus was collected from spikes of F. myuros after flowering in late April, and from citrus trees after death of the cover plant in May, which was 2 to 4 weeks earlier than in clean cultivations. The peak density of the citrus red mite in one of the sod cultures during the summer was one-fifth of that in the clean cultivation. In another orchard, N. californicus was collected from spikes of bermudagrass Cynodon dactylon or southern crabgrass Digitaria ciliaris from summer to autumn. Additional habitats consisting of several Poaceae ground covers flowering at different periods may stabilize the occurrence of N. californicus in the mandarin orange orchards in Japan.