The Polyphagous Shot Hole Borer (PSHB) is an invasive beetle that attacks common native and landscape trees, leading to branch dieback and overall decline. The disease stops the flow of water and nutrients in over 137 susceptible tree species, which can lead to the death of individual branches or, in severe cases, the entire tree.

Polyphagous Shot Hole Borer

In Laguna Niguel

Approximately 100 trees at Crown Valley Park and eight (8) trees at the Sea Country Senior and Community Center have been removed as a result of this disease. 

As drought conditions persist, it is expected that more trees in City parks, median islands, and slopes will succumb to this disease. City staff and contractors will continually examine City-owned trees to assess their viability. There are no preventive measures that can be taken at this time. By proactively removing the infected trees, the risk of harm from falling trees and limbs, as well as the spread of the disease, will be reduced. 

Reforestation Plan

As trees are removed to combat the disease, the City will plant new trees when it is cooler and potential rainfall will help them to get established. The replacement trees will be compatible with the surrounding area and resistant to attacks by the beetles. 


Residents are encouraged to check their trees for signs of infestation and distress

UCI News: Regional Beetle Infestation Prompts Removal of UCI Trees, April 17, 2015 article. 

University of Riverside, Eskalen Lab Information

Host Species
  • Box elder
  • Big leaf maple
  • Evergreen maple
  • Trident maple
  • Japanese maple
  • Castor bean
  • California sycamore
  • Mexican sycamore
  • Red willow
  • Avocado
  • Mimosa/Silk tree
  • English oak
  • Coast live oak
  • London plane
  • Fremont cottonwood
  • Black cottonwood
  • White alder
  • Titoki
  • Engelmann oak
  • Cork oak
  • Valley oak
  • Coral tree
  • Blue palo verde
  • Palo verde
  • Moreton Bay chestnut
  • Brea
  • Mesquite
  • Weeping willow
  • Chinese holly
  • Camellia
  • Acacia
  • American sweetgum
  • Red flowering gum
  • Japanese wisteria
  • Goodding's black willow
  • Tree of heaven 
  • Kurrajong
  • Black mission fig
  • Japanese beech
  • Shiny xylosma
  • Mule Fat