Agate Biosciences LLC - Science/Systems Engineering: Controlled Environment Agriculture
Polyphagous Shot Hole Borer (PSHB) is
Killing Trees Across Southern California

What is it?
Polyphagous Shot Hole Borer (PSHB), a tiny tree killing bug, from South East Asia, has infected trees across much of Southern California and has the potential of devastating our urban forests.  As it drills into the trees, it brings with it a fungus that infects the trees from the inside out and the trees die from the fungus, while the bugs move on to infect other nearby trees.  There is no treatment or cure - at this time.

PSHB  will drill into almost any tree to deposit its eggs and leave the fungus in its nurseries to feed the next generation of bugs.  The internal environment is perfect for the fungus to grow and thoroughly infect the tree.  Few trees can fight off this virulent infection.  They die because the fungus blocks the internal pathways for water and nutrients.  It is as if trees starve and thirst to death.  The internal core rots away, branches weaken, and leaves drop.  The trees must be cut down and chipped and taken away by professionals.  Never transport the wood that is cut from in infected tree.  It can spread the insect to new locations.

PSHB Checklist
Check your trees for the signs of PSHB infection.  If you find evidence of PSHB, contact the Country Agricultural Commissioner.  

We are still working to map the locations of the infected trees to determine true scale of the devastation caused by this insect and the resulting fungal infection.  You can help!  Check your trees now

Look for the following:

  • Tiny holes in the bark with weeping or crustiness oozing out
  • The holes frequently appear grouped in the first few feet above the ground or in branching off points
  • Drill holes with the sawdust (frass) left by the drilling PSHB
  • Leaves at the top of the tree that are falling off, while the rest of the tree still looks OK
  • Tree is not thriving for no apparent reason
  • Bark that appears deadened and loosely attached to the tree

PSHB will eat almost any tree.  It is particularly shocking because it is killing many, if not most, of our own California native species.  It has been found in Coastal Live Oak, Southern Live Oak, California Sycamore, Box Elder, Avocado, Maple, Magnolia, Willow, and many more.

Please join us to map this infection and help find a treatment and cure for this killer bug that will devastate our trees and leave our landscape barren of Nature's beauty.  Contact us if you would like to have a speaker come to your organization, club, or school to talk about PSHB and our program of identifying and mapping the spread of this tree killer.

For more information write to us at:

Write your observations of PSHB here:
Have you seen evidence of PSHB in your yard or neighborhood?
Drill holes with weeping
Drill holes with frass (sawdust)
Die off at the top of tree
In what trees have you seen evidence of PSHB?
What other trees have you seen with evidence of PSHB infection?
What is your Zip Code?

Website Builder provided by  Vistaprint