Oviposition Habit of the Japanese Pine Sawyer, Monochamus alternatus HOPE (Coleoptera, Cerambycidae) : I. Factors Affecting the Vertical Distribution of Oviposition Scars in a Pine Tree

Several experiments on oviposition habit of the Japanese pine sawyer, Monochamus alternatus HOPE were carried out at the campus of Kagawa University in 1989 and 1990. Adults were released into the small cage where logs of the Japanese black pine, Pinus thunbergii PARL. were set and oviposition scars on logs were counted. There was no significant difference in the number of scars on logs between the trunk and the branch. The number of scars on logs set in the horizontal position did not differ from ones in the vertical position. The mean number of scars per log cut from the branch became larger with the increase in the size of diameter. Many oviposition scars were made on logs which were cut at the middle part of the trunk and the number of scars decreased on logs cut from the lower or upper part. The relation between the vertical distribution of scars and the diameter of the trunk was discussed from the results.