The alien red turpentine beetle (RTB), Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure (south- and north-facing), host-tree locations according to relief (valley, mid-slope, and ridge-top) and tree diameters on RTB colonization were investigated in one valley (3 sites). The results showed that (i) RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; (ii) RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; (iii) RTB preferred to colonize trees with large diameter over small and medium-sized pines; (iv) the attack density of RTBs (measured by pitch tubes/pine) was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization pattes, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.