Abstract
Although Tetranychus urticae (green form) has never been found on the westernmost territory of Japan (the Yaeyama region of Okinawa Prefecture), we first observed the occurrence of this species from June to July, 2010, in greenhouses of fabaceous crops (kidney bean and cowpea) on one island of this region (Ishigaki Island). In October of this year, however, this species was not found in and around the greenhouses, strongly suggesting natural disappearance of this species. T. urticae can temporarily increase in the Yaeyama region, but it cannot colonize the region permanently, possibly due to some unknown biotic or abiotic factors specific to the region.
