Evaluation of two attempts to trap defined populations ofScolytus multistriatus.

Two experiments were conducted to investigate the use of a pheromone-based trap-out technique for suppressing populations ofScolytus multistriatus. In the first experiment, elm bolts containing the immature stages ofS. multistriatus were placed in an isolated community that contained elm trees, but which was essentially devoid of a resident beetle population. The infested bolts produced a total of 46,485 adult beetles of which 20% were recovered on traps baited with synthetic pheromone. In the second experiment beetles were released in a desert valley containing no resident elms or beetles. Only 1% of 20,000 released beetles were recaptured on traps erected on vertical cardboard cylinders and on elm logs. These rates of recapture are related to the attraction of beetles to naturally occurring brood sources versus pheromone-baited traps.