Pine Bark Beetles

Pine bark beetles in Arizona are generally of the genus Ips or Dendroctonus. However, several other genera also attack pine, including: Hylastes, Hylurgops, and Pityogenes. Often several species will attack at the same time. Identification of specific beetle species can be difficult. Identification can be aided by knowing the host species attacked, time of year, and the design of the galleries (tunnels) created by the adults and larvae.

Bark beetles contribute to the death of thousands of ponderosa pines in Arizona each year. Most often when larger trees are attacked and killed they have been weakened by drought, lightning, construction activity or they have been growing on poor sites. Of special concern is the loss of high-value trees at home sites or in developed recreation areas.

Evidence of infestation

Fading foliage in the tree is often the first sign of a beetle attack. Trees attacked by Ips spp. typically fade from the top of the crown downward, while Dendroctonus spp. killed trees fade from the bottom of the crown upward. The needles change from green to a light straw color within a few weeks to one year after attack and eventually become brown or red. Dust caused by boring in the bark crevices and at the tree base is another sign. Often, numerous small pitch tubes globules of pitch ³/4 to 1 ¹/4 ” diameter) appear on the trunk of infested trees.

This article was written by 
Tom DeGomez, County Agent and 
Deborah Young, Associate Director.