Sirex nitobei is a completely dark form species known from East Asia (Smith 1978).
See Sirex for genus-level diagnostic characteristics.
The female Sirex nitobei can be distinguished from S. imperialis by the mostly light-colored legs (Benson 1943). Males can be distinguished from S. rufiabdominis by the median and lateral post ocellar furrows (Xiao and Wu 1983).
Sirex species feed on trees of Pinaceae and Cupressaceae. Sirex nitobei is recorded feeding on Larix kaempferi (Japanese larch), Pinus thunbergii (Japanese black pine), Pinus densiflora (Japanese red pine), Pinus armandii (Chinese white pine), other Pinus sp., and Abies firma (momi fir) (Okutani 1963, Smith 1978, Xiao and Wu 1983, Tabata et al. 2012).
Female Sirex harbor symbiotic basidiomycete fungus in abdominal glands called mycangia. During oviposition, the site is inoculated with the fungus (Amylostereum spp.), which begins to decompose the surrounding wood. Larvae feed on the fungus, and in the process bore galleries through the wood (Schiff et al. 2012). The mycangia of S. nitobei harbors Amylostereum areolatum fungus (Tabata et al. 2012).
Larvae are creamy white and grub-like in appearance with a dark head capsule. As with adults, larvae possess a short dorsal horn on the posterior end of the body. The larvae bore galleries into wood, feeding until pupation and subsequent emergence. Throughout this process, the larvae use their horn to pack the tunnel behind them with sawdust. Emergence holes are perfectly circular. The fungal symbiont is carried in specialized organs in female larvae that develop into the mycangia after metamorphosis (Schiff et al. 2012).
The documented flight period of S. nitobei is August to mid-October (Tabata et al. 2012). Adults live for only four days. There is evidence that this species has a preference for damaged or dying trees. However, the damage caused by the insect and the discoloration of the wood due to the fungus growth reduces the value of the lumber (Tabata et al. 2012).
North America: not recorded
Map data from: GBIF.org (26 June 2019) GBIF Occurrence Download Sirex nitobei
Details about data used for maps can be found here.