What is the Mountain Pine Beetle?

With recent dry and drought conditions in our Foothills (Conifer, Bailey, and Evergreen) this native insect has once again resulted in the decline and loss of pine trees. It attacks four species, while one species is not native to our local Foothills, the Scotch Pine. The remaining three are Ponderosa Pine, Lodgepole Pine, and Limber Pine. Our Foothills are forested with old growth Ponderosa and Lodgepole pines, while Limber pines prefer a little more elevation.

They are currently attacking trees in groups, while spreading throughout the hills like wildfire. With our current dry conditions, the beetles are quickly proliferating, and trees are not able to manufacture enough pitch (Sap) to kick the insect out. Once the female is inside the host she will lay her eggs, that will have into larvae that create tunnels as they feed upon the vascular tissues of the tree. The larvae produce glycerol that assists them in surviving the winter months. As temperatures rise in the spring and the tree’s sap starts to flow again, the larvae will begin feeding until they pupate to become adult beetles. Adult beetles begin to emerge in June, with July being the biggest emergence month. They will continue to slowly emerge until sometime in September (as not all eggs, larvae and pupae mature at the same rate). The insect has a one-year life cycle (meaning they produce one generation per season). These beetles are related to IPS Engraver Beetles and can carry the pathogen, Blue Stain Fungi on their mouthparts and transmit it into the host tree upon entering. This Blue Stain Fungi clogs up the vascular tissue within a tree slowing the movement of nutrients and water vital to a tree’s survival.