Abstract
Predation by insects on the larvae of the Japanese pine sawyer, the vector of pine wilt disease, was investigated in the field by a method comparing the proportions of empty pupal chambers from red pine bolts, in which oviposition had already been undertaken by the beetles, whether exposed or covered with double mesh cloths or lmm mesh cages in July, 1995. At Yasu, Shiga Prefecture, where the bolts were opened in December this year, the proportions of empty pupal chambers, in which the larvae must have been fed on by the predator, were very high from un-bagged bolts placed near the ridge of a hill where more red pine trees died than at the foot of the hill, and a maximum of 63.5% of the larvae in the pupal cambers were estimated to be fed on. But at Fushimi, Kyoto, where bolts were not opened until next April, the proportions of empty pupal chambers were very low at or near the site where many newly cut red pine bolts were laid on the floor regardless of the environment of the placement sites. As a result, predation might be affected by the amount of newly dead pine trees.
