Deladenus nitobei Kanzaki, Tanaka, Fitza, Kosaka, Slippers, Kimura, Tsuchiya & Tabata, 2016 was originally described as an internal parasite of a woodwasp species, Sirex nitobei Matsumura, that emerged from dead logs of Japanese red pine, Pinus densiflora Sieb. & Zucc. collected from Takko, Aomori, Japan (Kanzaki et al., 2016). During the collection of material for the species description, the emergence date and sex of the wasps were recorded, and the dissected wasp bodies were fixed in 100% ethanol and vouchered at the Forest Pathology Laboratory of Forestry and Forest Products Research Institute, Tsukuba, Japan. We re-examined the vouchered materials of the wasps and measured their body size, comparing it with the presence/absence of nematode parasitism to provide additional information about the relevance of parasitism in relation to the emergence season of the wasps.