Monitoring and Detecting

The first step to managing spruce budworm in the context of an early intervention strategy is to detect and monitor where populations are rising before they reach relatively high densities.

Spruce budworm populations are monitored and detected in several ways:

  1. Aerial defoliation surveys in July to detect defoliation when feeding of spruce budworm larvae cause the trees to turn red. These areas are detected by observers in an airplane and sketched on a map to define where defoliation occurred.
  2. Surveillance from the ground for signs of spruce budworm feeding and the presence of spruce budworm larvae and other life stages such as pupal cases. Observations of either budworm feeding or life stages would be evidence of elevated populations (for more information on what spruce budworm looks like, please visit this link).
  3. Pheromone and light trapping of adult moths provide baseline information on local spruce budworm population densities. See our map for current information.
  4. Branch collections for overwintering larvae provide forest managers with a forecast of budworm density in the following year, which can be used to estimate defoliation level. The overwintering larvae are often referred to by scientists as second instar budworm or “L2” for short. See our map for current information.

The basis of the early intervention strategy is to detect when and where populations begin to rise and then to target those areas for treatment. To accomplish this, it will be necessary for citizens to be engaged in this process. The province has a role in monitoring and woodlot owners and everyday citizens can help by being vigilant for the characteristic reddening of spruce and fir that result from defoliation, a prime indicator of spruce budworm feeding. For more information on how to participate in spruce budworm pheromone trapping through our citizen science project, please click here. If you think you have found spruce budworm within New Brunswick, please contact the New Brunswick Natural Resources at 506-453-3826 or e-mail