Survey of Records of Restoration in Relation with Damage by Wood-boring Insects at Rinnohji Temple in Nikko

A very rare anobiid species in Japan, Priobium cylindricum, was found by chance in the restoration work of the Sambutsu-do of Rinnohji temple in 2008. The insect caused very severe damage in hard (heart) wood. The inside of beams, pillars and smaller wooden pieces was extensively damaged to a powdery state. However, damage was not clear by observation from the outside of the structure, especially when seen from the red painted thick layer of urushi. Such damage was more obvious in the recycled older wooden pieces, which suggested a possibility of the survival of the insects in the recycled wood. Records of previous restoration were examined, especially with photos of the restoration made from 1954 to 1961. Extensive damage was seen at the restoration at that time. The damage seen in the records and photos seemed to have characteristics similar to the recent damage by Priobium cylindricum. From the comparison of the characteristics of damage, it was suggested that Priobium cylindricum might have been involved in the similar damage to the building at the time of restoration several decades ago.