Surveying for Douglas-Fir Tussock Moth with Pheromone

One of the biggest problems we face in trying to prevent damage by the Douglas-fir tussock moth is knowing when an outbreak is going to occur. In the past, we have only detected outbreaks that are advanced sufficiently to be seen by aerial survey. When this happens, much of the damage has already been done, as trees are often half defoliated and sometimes completely defoliated in that first season. If we could learn about an imminent outbreak 1 to 2 years before it happens, we could be prepared and perhaps prevent excessive damage from occurring. Conventional methods of population sampling, such as surveys of larvae and egg masses, have not proved adequate to detect the initial stages of an outbreak. The female tussock moth is flightless and produces a pheromone that attracts the male moth. We sought to use this pheromone in a trapping system that would enable us to monitor the population and give the desired lead time on a potential epidemic.