Bark Beetle Activity in Central and Northern Arizona in 2021

Graphic of a bark beetle Higher than normal levels of tree mortality have been reported in Arizona during the winter and spring of 2021. Most of the mortality appears to be related to drought stress and pine engraver attacks on ponderosa pines. In particular, increased pine mortality has been observed on the Prescott, Kaibab and Coconino National Forests, and along the Mogollon Rim on the Apache-Sitgreaves National Forests. Pine mortality has been concentrated in lower elevation sites, southern exposures and where trees are chronically stressed due to intertree competition and dwarf mistletoe infection. The photograph below shows some of the tree mortality.

Photograph of a group of dying ponderosa pine trees attacked by Ips bark beetles

Dry Conditions

Bark beetles are known to attack water stressed trees and tree mortality was anticipated given the low amount of precipitation received over the previous year. Attacked trees may have pitch tubes, however, during dry years only the boring dust or frass (circled in the image below) may be present.

Close-up photograph of bark on a ponderosa pine showing frass from bark beetle attack

Status

Forest Health Protection will monitor the tree mortality with continued ground surveys and during our annual aerial surveys to determine the extent across the landscape. Results from these surveys will be available and reported in our annual conditions report.