ATTRACTION OF STEAMED JAPANESE LARCH (LARIX LEPTOLEPIS (SIEB. ET ZUCC.) GORD.) HEARTWOOD TO THE SUBTERRANEAN TERMITE COPTOTERMES-FORMOSANUSSHIRAKI (ISOPTERA, RHINOTERMITIDAE)

The attraction of steamed Japanese larch (Larix leptolepis (Sieb. et Z ucc.) Gord.) heartwood to the subterranean termite Coptotermes formosa nus Shiraki was investigated with choice tests and no-choice tests. Wo od samples were prepared from green larch boards steamed at 170 degree s C for 30-240 min. In a choice test and a no-choice test, weight loss es due to the termite attack were very small in non-steamed samples wh ile they were large in steamed ones. Steamed samples extracted with ho t water were not attacked by termite in a choice test. Japanese cedar (Cryptomeria japonica D. Don.) wood specimens treated with water solub le fractions from the hot water extractives of larch were preferably a ttacked in a choice test. These phenomena suggest that steaming produc es attractants and degrades, removes and/or modifies some larch wood c onstituents which suppress the termite attack.