Bark Beetle Infestation Devastates 90-year-old Urban Coulter Pine Forest At Pinecrest Gate

Over the last several weeks, the County of Los Angeles Department of Public Works has been dealing with an outbreak of bark beetle in a stand of Coulter Pines at roughly one dozen private residences near the Pinecrest Gate. These pests, which invade trees by flying from trunk to trunk, have been killing this stand of Coulter Pines that have been growing for roughly 90 years in the area. Once the beetle bores a hole in the tree’s trunk, it begins eating the cambium layer, the tree’s living tissue. This stops the tree from being able to get water and nutrients to its leaves, and carbohydrates back down to its roots. These beetles can kill the tree in a matter of weeks. While healthy trees may be able to push the beetles out with sap, trees stressed by drought and/or fire such as these are less capable. 

This loss comes at a time when Altadena has already been dealing with the significant loss of its urban forest due to the Eaton Fire and questionable business practices from tree-trimming companies that followed. It is unclear how many total trees could be lost in this outbreak, but the number already stands at 11. Coulter pines are native to California but are not historically found at Eaton Canyon, especially in lower elevations.