Natural History of the Southern Pine BeetleThis article is part of a larger document. View the larger document here.
The southern pine beetle (SPB) is a tree killer of southern yellow pines. All life stages—eggs, larvae, pupae, and adults—infest the inner bark or phloem tissue of the host tree. Adult beetles overcome the tree’s defenses through a mass-attack phenomenon. They are attracted to the tree by a pheromone system consisting of volatiles produced by the beetles and the host. The pheromone system also prevents the beetles from over-colonizing the tree. Once inside the tree, parent adults construct serpentine egg galleries in the inner bark tissue. Individual eggs are deposited in egg niches along the egg gallery. After eclosion, the larvae develop on host tissue, and development is aided by mycangial fungi deposited in the egg galleries by the adult females. Pupation occurs in the outer bark, and brood adults emerge to attack another nearby tree. As this process continues infestation spots of dead and dying trees can be created. Generally an SPB spot gets its start on stressed and weakened tress. Depending upon climate, the number of SPB generations per year can vary from one to nine. The SPB has the capacity to cause periodic large-scale eruptions that encompass entire regions of the South. Host resistance, predators, parasites, diseases, and competitors all keep SPB populations in check during nonepidemic years.