We examined host utilization pattern of the kleptoparasitic spider Argyrodes kumadai along a geographical gradient from central Japan to southwest Islands. Host species changed abruptly between Yakushima Island and Amami-oshima Island: Agelena silvatica (Agelenidae) in northern regions and Cyrtophora moluccensis (Araneidae) in southern regions. This is the first report showing allopatric host change in kleptoparasitic spiders.
