Invasion by the goldspotted oak borer killed thousands of valuable oaks in southern California since the late 1990s. A Northern Research Station scientist and his partners developed a risk map to highlight where this insect might spread next. The risk map has become the backbone of survey and management efforts for the insect by the Cleveland, San Bernardino, and Los Padres National Forests to protect remaining oak trees.

The goldspotted oak borer (GSOB, Agrilus auroguttatus), a nonnative invasive species, has killed tens of thousands of oaks, particularly coast live oak, California black oak, and canyon live oak, in southern California. Larvae of this insect feed beneath the bark, disrupting the flow of water and nutrients. Dead oaks become a hazard to recreationists and increase fuel loads for fire. A Northern Research Station scientist and colleagues from the Pacific Southwest Research Station and Region 5, Forest Health Protection staff conducted biological and modelling studies in rapid response to the pest invasion to gather the necessary information to generate a risk map to highlight where GSOB has been reported, where suitable habitat for the insect likely occurs, and where the insect might spread next. The Cleveland, San Bernardino, and Los Padres National Forests in southern California rely on the risk map as the backbone of survey and management efforts. The map is also used in “Don’t Move Firewood” campaigns, highlighting areas where accidental introductions of the insect could kill thousands more trees.