MPB release a pheromone when they find areas of trees that are good candidates for infesting.  They emit a different pheromone when an area has reached its capacity for new infestations.  There are pouches on the market that emit the “no vacancy” pheromone that be used to deter beetles from infesting an area. 

Pheromone pouches should be applied immediately before the MPB flight to ensure maximum effectiveness.  There are different tactics used in placement of pheromones but a general guideline is 30-60 pouches per acre.  The effectiveness of pheromones once again depends on the local level of infestation.  In areas of heavy infestation the effectiveness of pheromones has proven to be minimal.  They are a good choice for areas around water that cannot be sprayed and can be effective when used in conjunction with other treatments especially spraying.