Casey from Pasadena, Ca writes
I have been trying very hard to spot the actual beetles but have not seen any. I do however, see a bald patch of trunk on my black pine with what looks to be 3 woodpecker holes. Some branches have all brown needles. In cypress trees nearby, I see trails of yellow sap seeping out and some branches there already turned brown. I'm so so sad as this black pine is a very fancy Japanese bonsai style tree and I might have lost a few small trunks with the brown needles.
An insecticide such as Demand CS can be used to prevent infestations of bark beetles such as pine bark beetles, however usually this treatment is not effective once trees are already infested. You want to spray down the trunks of nearby trees to protect them from infestation. You may need to consult a local arborist if you are unsure whether the trees can be saved. You can usually trim and destroy infested branches, however keep in mind that this pest will usually infest trees that are already weak from some other existing issue (disease, drought, etc.).
Answer last updated on: 01/07/2021