Host-Finding Behavior of the Douglas-Fir Beetle

Abstract Research over the past 10 years has shed new light on the host-finding behavior of the Douglas-fir beetle. Whereas it was once thought that the beetles emerged from down timber to attack trees in the near vicinity, it is now known that most standing trees are killed when beetles attracted into freshly downed timber "spill over" into standing trees near by. In most any year beetle attacks can be found in standing trees close to sources of attraction, however, it is only in years following severe windthrow that the beetle populations are great enough to cause significant tree killing. Suggestions are given for reducing damage caused by the Douglas-fir beetle.