Various preservative treated or modified wood stakes other than CCA, were buried in the soil, maximum for six years in Kumamoto, south west side of Japan. In this area, two main termite species, Coptotermes formosanus and Reticulitermes speratus, are distributed. After two years in field, untreated sapwood of sugi (Cryptomeria japonica) were observed severe attacks by termites, but the preservative treated stakes were observed no significant attacks by termites. After six years, treated stakes with preservatives not included copper, like DDAC and zinc-naphthenate, were observed slight or moderate attacks by termites. Otherwise, in the case of treated stakes with preservatives included copper, like ACQ, copper naphthenate and Tanalith CuAz, no significant attacks by termites were observed. Few samples of chemically modified wood or LVL were observed slight attacks by termites for four years.

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