Distribution

Since its discovery in San Diego County in 2008, Goldspotted Oak Borer (GSOB) infestations have spread throughout the county and beyond. Satellite GSOB infestations were identified in Riverside County in 2012, Orange County in 2014, and Los Angeles County in 2015. A second satellite infestation was discovered in southeastern Orange County in 2017. The latest GSOB satellite infestations were found in San Bernardino County in 2019 and 2020. These satellite infestations are believed to have occurred due to people transporting GSOB-infested firewood from known infested areas.

The California Board of Forestry and Fire Protection originally declared a Zone of Infestation (ZOI) for GSOB on September 12, 2012. This was an official and formal action to (1) recognize GSOB as a threat to California’s forest and woodland resources, and (2) to combat GSOB while providing the public with important information. The ZOI has since been expanded twice (in 2014 and 2016) to include new areas of infestation and areas with increased risk to host oak trees.

Maps of the current ZOI as of 2020 are shown below by region: Southern California, and by county: San Diego, Riverside, Orange, Los Angeles, and San Bernardino.

Maps courtesy of Kim Corella at CalFire

GSOB Zone of Infestation in San Diego, Riverside, Orange, Los Angeles and San Bernardino Counties

(2020)

GSOB Zone of Infestation Map: San Diego County

(2019) Note - Since 2019, the majority of San Diego County has been designated a GSOB Zone of Infestation. There were no changes in 2020.

GSOB Zone of Infestation Map: Riverside County

(2020)

GSOB Zone of Infestation Map: Orange County

(2020)

GSOB Zone of Infestation Map: Los Angeles County

(2020)

GSOB Zone of Infestation Map: San Bernardino County

(2020)

GSOB was detected in recently-killed and dying California black oaks (Quercus kelloggii) in these unincorporated communities in San Bernardino County:

Spring 2020 – Forest Falls area
October 2019 – Wrightwood area
August 2019 – Sugarloaf community and Moodridge area near Big Bear
November 2018 – Oak Glen area