A cephaline gregarine which has segmentation in deutomerite is found from dixa sp. In Yamaguchi, Japan. The mosquito larvae are occasionally captured in paddy fields or in small streams from winter till spring. They are easily found because of their blackish body color and of characteristic habit of sitting on something at the water edge and of bending the abdomen in the shape U. Almost of the larvae are parasitized by this gregarine. About 90% of the larvae collected near around Miyano, Yamaguchi City last winter, 1967, were lodged by this species. The number of parasites obtained from one host was not so large and 3 or 4 was common, however, more than 30 parasites rarely live in the host's intestine at a time. If one puts the whole digestive tract between two plates of slide glass and examines it under microscope, one can easily recognise the position and state of the parasite. The parasite generally sticks to the wall of middle or posterior region of the intestine (Fig. m).