Illinois Insights - Anderson's Tree Care Specialists Puts Saratoga and Los Gatos Oaks on Watch as Oak-Killing Beetle Moves North

Anderson's Tree Care Specialists Puts Saratoga and Los Gatos Oaks on Watch as Oak-Killing Beetle Moves North

Sep 24, 2026

Fall is firewood season across the South Bay, but this year, that familiar ritual carries an unfamiliar warning. In January 2026, CAL FIRE confirmed that the goldspotted oak borer Bay Area threat is advancing, with the beetle reaching Ventura County. This marks the sixth confirmed California county it’s been documented in and the farthest north it has ever been found. Two months later, CAL FIRE issued a statewide advisory asking Californians to "Buy It Where You Burn It," targeting the one pathway the goldspotted oak borer depends on for long-distance spread: infested oak firewood moved across county lines.

Fortunately, the beetle has not yet been confirmed in Santa Clara County. Anderson's Tree Care Specialists, a family-run ISA-certified arborist tree service company serving San Jose, Saratoga, Los Gatos, and the surrounding South Bay communities, wants to keep it that way. In response to the beetle's northward advance and the elevated risk that firewood season introduces, Anderson's is expanding its oak inspection scheduling in Saratoga,as well as their tree pest and disease control services in San Jose across Saratoga and Los Gatos. This will hopefully give homeowners with mature oaks on their properties a direct path to professional evaluation before any problem takes hold.

"By the time most homeowners notice something is wrong, the infestation is already well established. We can still help at that stage, but the window is smaller than people expect. If you have oaks on your property in Saratoga or Los Gatos, don't wait for the obvious signs."
— Anderson's Tree Care Specialists, ISA-Certified Arborists

Anderson's Tree Care Specialists is a fully licensed, bonded, and insured family-run tree service in Saratoga, CA, and the Los Gatos area, based in San Jose, California, and serving the broader South Bay region. — Anderson's Tree Care Specialists

The Goldspotted Oak Borer: What South Bay Homeowners Need to Know

The goldspotted oak borer is a wood-boring beetle native to southeastern Arizona that was first detected in San Diego County in 2004. It has since spread progressively northward through California, and the January 2026 Ventura County confirmation represents its most significant geographic jump yet. The beetle attacks several native California oak species, including coast live oak, California black oak, and canyon live oak, by boring beneath the bark to lay eggs, disrupting the vascular tissue that carries water and nutrients through the tree. Heavy infestations kill oaks outright, often within a few years of initial attack.

Unlike many airborne tree pests, the goldspotted oak borer does not spread primarily through wind or wildlife. Its only confirmed long-distance pathway is the movement of infested oak firewood. When firewood cut from an infested tree is transported across county lines and burned or stored outdoors near healthy oaks, beetle larvae can emerge and establish new populations. That is why CAL FIRE's "Buy It Where You Burn It" advisory is directed specifically at firewood buyers, not just land managers or commercial operators.

For homeowners in Saratoga and Los Gatos, the practical implication is straightforward: Do not purchase or transport oak firewood from southern California counties, and have a qualified arborist in Saratoga, CA, assess any oaks showing signs of stress before this fall's firewood season is fully underway.

Warning Signs Homeowners in Saratoga and Los Gatos Should Watch For

Through Anderson's tree pest and disease control program, certified arborists have identified the following early-warning symptoms as the most reliable indicators that a tree may be under active pest or disease pressure. Any one of these warrants a professional evaluation.

Yellowing, wilting, or premature shedding of leaves or needles. Canopy decline that progresses faster than seasonal norms, particularly on one side of the tree or in isolated branches, often signals a systemic vascular issue. In the case of the goldspotted oak borer, this reflects damage to the phloem tissue the beetle destroys as it bores beneath the bark.

Small holes or D-shaped exit holes in the bark. Tiny entry and exit holes, often accompanied by fine sawdust-like material called frass at the base of the trunk or on the bark surface, are a direct signature of active bark beetle boring activity. The goldspotted oak borer leaves a distinctive D-shaped exit hole approximately 4 to 7 millimeters wide. These should be evaluated immediately.

Sunken cankers, staining, or blotches on the bark surface. Discolored, sunken, or weeping areas on the trunk or major limbs can indicate the bark death that often follows goldspotted oak borer attack, or fungal canker disease that frequently travels in tandem with beetle infestations. Either can girdle and kill entire branches — or the whole tree — if left untreated.

What Anderson's Oak Inspection and Pest and Disease Control Services Deliver

ISA-certified arborist diagnosis: As ISA-certified arborists in Santa Clara County, Anderson's tree health professionals use industry-leading diagnostic techniques to identify pest and disease issues at their earliest stages, when treatment options are broadest and the cost of intervention is lowest. Every oak inspection Saratoga appointment includes an assessment of surrounding trees for signs of spread.

Customized treatment plans targeting both insects and fungal pathogens: Whether the threat is bark beetles, parasitic fungi, scale insects, or a combination, Anderson's develops treatment plans specific to the species, the infestation stage, and the site, rather than applying generic solutions that may miss the underlying driver of decline.

Spread containment and neighboring tree evaluation: An infected tree that is left untreated can rapidly transmit pests and disease to nearby trees. Anderson's pest management protocol includes inspection of adjacent trees to determine whether the infestation has already moved, and intervening before it does if it has not.

Homeowners in Saratoga and Los Gatos with mature oaks or other established trees on their properties are encouraged to schedule a no-obligation consultation before symptoms advance. As the trusted tree service company in Saratoga and Los Gatos for oak health and pest management, Anderson's is accepting fall inspection appointments now. Evaluations can be arranged by calling (408) 226-8733 or through andersonstreecare.com.

About Anderson's Tree Care Specialists

Anderson's Tree Care Specialists is a fully licensed, bonded, and insured family-run tree service in Saratoga, CA, and the Los Gatos area, based in San Jose, California, and serving the broader South Bay region. The company's ISA-certified arborist team in Santa Clara County provides tree removal, stump removal, tree trimming and pruning, tree and plant healthcare, tree planting, and emergency tree services. Anderson's is a member of the TCIA and has a staff that includes several ISA-certified arborists. License number: 705171. To schedule a no-obligation consultation, call (408) 226-8733 or visit andersonstreecare.com.