A Paraisaria-like fungus isolated from a larva of a cerambycid beetle, Anopolophora oshimana, produced small obovoid conidia from multi-necked conidiogenous cells arising from synnematous conidiophores. In culture, the fungus produced curved Harposporium-like conidia in addition to obovoid conidia. When introduced into nematode-infested cultures, nematodes were infected after ingesting the curved conidia and infection typical of Harposporium, producing curved conidia from globose conidiogenous cells, resulted. Reinfection of beetle larvae by injection of hyphal bodies from pure culture and by contact with conidia from the original host showed pathogenicity to cerambycid larvae.