I was pleased to see your June 11 article about invasive shothole borers (ISHB) in the Santa Monica Mountains, which may help to bring attention to this little known pest affecting local trees. However, I did think the article was a bit alarmist and also misleading in its implication that nothing can be done about infested trees.
When Resource Conservation District of the Santa Monica Mountains (RCDSMM) biologist Rosi Dagit refers to the beetle problem reaching “epidemic proportions,” I believe she is referring to Southern California as a whole, rather than the Santa Monica Mountains specifically. Invasive shothole borers have killed tens of thousands of trees in Southern California, but the impact in the Santa Monica Mountains has not yet been fully determined. That is the reason behind RCDSMM’s volunteer-driven Bad Beetle identification project and efforts by the Los Angeles County Agricultural Commissioner’s Office to survey and trap beetle populations in the area.
Also, while it is true that severely infested trees generally cannot be saved and should be removed to eliminate hazards and prevent spread of the beetles, low to moderately infested trees can be treated successfully, often just with removal of infested branches. Anecdotal evidence indicates that when severely infested trees are removed from an area, the remaining low and moderately infested trees can recover over time, especially with ongoing monitoring and maintenance. Chemical treatments also may be appropriate in some circumstances but are never a first course of action. Funding for removal of severely infested trees may be available through the agricultural commissioner’s office. Other actions to stop the spread of wood-boring insects include proper green waste disposal and not moving firewood.
Early detection is the most critical element in controlling this pest. Signs and symptoms of infestation include the entry holes mentioned in the article, staining, sugar-like buildup, gumming and boring dust. Residents should be on the lookout for these signs of attack and can use the detection and management assessment tool found at www.ishb.orgto get management advice and report new locations of infestation. Additional information about the pest is available at the website.