A new invasive pest threatens to wipe out the 175 Million trees in California’s urban forests.

Imagine your neighborhood without trees.

Hotter temperatures. More pollution.
Immense costs to the economy and our quality of life.

Please watch this video to learn more about the threat, then read below to learn what you can do to help.

What you need to know:

“The host range of this pest is huge.”
Tim Spann, Research Program Director, California Avocado Commission

“It’s ground zero… I don’t think the public really has a clue how devastating this potentially is… and it’s rapidly spreading…”
Dr. Glenda Humiston, Vice President, University of California, Agriculture and Resources

  • Unlike other pests, Invasive Shot-Hole Borer (ISHB) attacks many species of trees – between 50 and 150 species!
  • It prefers trees that are irrigated like trees in cities, the suburbs, river valleys, and riparian areas.
  • The ISHB has been found from San Diego all the way up to Santa Barbara and spotted in San Luis Obispo.

“The numbers in Southern California are astronomical… It is only a matter of time before it gets to Northern California”
Dr. John Kabashima, Environmental Horticulture Advisor, University of California

Recommended resources:

What you can do:

1. Share this page with your friends

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2. Check your trees

Check your trees and the trees in your neighborhood on a regular basis — especially the California sycamores — the pests like these trees best. See “What to look for” below. If you see small holes and stains on trees like in the photos, contact your local arborist and county agricultural commissioner.

3. Do not move firewood from your neighborhood!

4. Chip your green waste to 1 inch or less.

5. Contact your representatives

Call and/or send an email to your state representatives to ask for funding and strong public policy to combat this pest. (Find your representative’s contact information on OpenStates.org.) Here are a few possible talking points:

I’ve just heard about the Invasive Shot-Hole Borer pest, and I’m very concerned about the threat to the trees in my neighborhood and in California overall. This pest could wipe out the trees in my town if we don’t do something to stop it now.

Losing large numbers of urban trees to this pest would be terrible for the health of my community and the quality of life in my neighborhood. We wouldn’t have any shade so it will get much hotter and air quality will get much worse.

I urge you to support strong policy and significant funding — such as Assembly Member Lorena Gonzalez Fletcher’s bill AB 2054 with an allocation of $5 million to stop this pest from destroying the trees in our cities and riparian areas.

[Share a personal story about why you want to keep your trees or how trees help your neighborhood.]

What to look for:

The ISHB is tiny – practically a dot on a penny.

Stains from the ISHB.

Entry-holes are round and less than a mm wide, about the size of a ball-point pen tip.

Currently the Invasive Shot-Hole Borer’s favorite tree is the California sycamore, so check the sycamores in your neighborhood first, to see if there are small holes and dark stains. Around the entry-hole, look for dark, wet staining that sometimes dries to white or yellow; thick gumming; white, powdery exudate; and/or frass, which resembles sawdust. Please download the ISHB Field Guide (.pdf, 48 pages) for more detailed information on how to identify ISHB and many more host tree species.

Identifying the California sycamore

California sycamore

California sycamore – bark detail

California sycamore – leaf detail