Infestations by stem borers in teak (Tectona grandis) and yemane (Gmelina arborea) plantations were surveyed at seven locations in Sabah, Malaysia in March, 1998. The teak beehole borer (Xyleutes ceramica) and the collar ring borer (Endoclita aroura) were found to attack teak and yemane. X. ceramica accounted for most of the boring attacks in teak plantations, damaging 10.3-65.2% of the planted trees, except at one location where no stem borer attack was detected. The number of past and present attacks per tree ranged from 0.27-1.28 and 0.01-0.62, respectively. In contrast, E. aroura was of minor importance, attacking 6.9% or less of the planted trees. Analysis of spatial distribution of past attacks by the teak beehole borer in young teak stands revealed a contagious pattern. The past attacks were heavier on bigger trees. Both past and present attacks were concentrated in the lower part of the trunk, less than 1 m from the ground level. In young stands of yemane, an unidentified lamiine cerambycid damaged 0.0-14.1% of the trees, whereas the teak beehole borer damaged 7.6-12.2% of the trees.