キシャヤスデ類の大発生

抄録

The train millipedes, Parafontaria laminata group, are endemic in Central Japan and notorious for stopping trains during their outbreaks. Recently, it was established that the train millipede contains 3 species and 1 subspecies (P. laminata laminata ATTEMS, P. laminata armigera VERHOEFF, P. kuhlgatzi VERHOEFF and P. echizenensis SHINOHARA). The distribution of each species is restricted to a certain locality. P. laminata armigera is distributed in the mountainous region of Central Japan. Outbreaks occurred in autumn, at 8 year intervals, or in both 7th and 8th years in this region. The outbreak population consisted mainly of adults, but also 7th instars at times. The adult P. l. armigera laid eggs early in the next summer and died. The eggs hatched in the summer and the 1st instar larvae hibernated in the winter without molting. The larvae lived in the soil, molted once a year, and became adults after the 7th molt. The adults and some 7th instars swarmed on the soil surface in autumn, which was regarded as the outbreak. The swarming records of the other train millipedes were arranged according to the locality, although the periodicity of the outbreak is not clear.