The Polyphagous Shot Hole Borer (PHSB) Euwallacea sp., is an invasive beetle that carries two fungi (Fusarium euwallaceae and Graphium euwallaceae.) The fungi causes a disease called Fusarium Dieback (FD), which interrupts the transport of water and nutrients in over 138 tree species. Trees may experience branch dieback, canopy loss, and tree mortality. Once the beetle/fungal complex has killed the host tree, pregnant females fly in search of a new host. Both the fungus and beetle have been identified in trees in Southern California. The beetles attack landscape, agricultural, riparian, and native trees.
Adults are oval in shape and brown to black in color. Adult females are approximately 2.62 mm long and 1.07 mm wide. Males are smaller, approximately 1.8 mm long and .81 mm wide. Only females are able to fly. Immature stages (eggs, larvae, and pupae) are white in color.
- Big Leaf Maple
- Box Elder
- California Sycamore
- Coast Live Oak
- English Oak
- Japanese Maple
- London Plane
- Willow Species
Full list: http://ucanr.edu/sites/pshb/
SIGNS AND SYMPTOMS
EXTERNAL - staining, gumming, or sugar exudate response to outer bark; beetle exit/entry holes (approximately .85 mm).
INTERNAL - brown to black discoloration of wood.
For additional photos of signs and symptoms, please review this handout from UC Division of Agriculture and Natural Resources.
WHAT TO DO IF YOU HAVE AN INFESTED TREE
ON A RESIDENTIAL OR BUSINESS PROPERTY
To prevent the spread of the beetle and disease - do NOT move wood out of infested area, including firewood.
Unfortunately, there are no effective treatments against the pest/disease complex.
1) If symptoms are found on an infected tree branch - cut and dispose the infected tree branch, double bag it and place it in your trash bin.
2) Your tree will require proper care to regain health. Continue to provide water and nutrients to the tree.
This handout can guide you through deciding when to remove an infested tree, and how to handle the wood waste.
You may report infested parkway trees to
Forestry Services at: 818.238.5304
UC Agriculture & Natural Resources, UC Riverside Center for Invasive Species Research, US Dept. of Agriculture - Forest Services, County of Los Angeles Agricultural Commissioner
Photos Courtesy of Dr. Akif Eskalen, UC Riverside Center for Invasive Species Research.
- www.pshb.org - UC Division of Agriculture and Natural Resources research-based information on polyphagous shot hole borer for educational purposes
- UCANR Green Bulletin
- Identification Handout
- LA Times Story: "What to do if the polyphagous shot hole borer attacks your trees"
- Plant Heroes Activity Book
RECURSOS EN ESPAÑOL