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Borers in Eucalyptus and Valley Oak: Likely Longhorn Beetles

Identification

Damage in both eucalyptus and valley oak in Bakersfield foothills strongly suggests Eucalyptus Longhorn Borer (Phoracantha spp.), which attacks stressed eucalyptus and can move to nearby oaks.

Treatment

Soil drench with Bayer Advanced Tree & Shrub Insect Control (imidacloprid) around each affected tree. Systemic action kills larvae inside and protects for a season.

Sanitation

Remove and destroy heavily infested eucalyptus (chipping, burning, or solarizing logs).
Keep trees vigorous: deep water during drought, mulch, avoid trunk damage.

Trees: Cherry Tree Gummosis: Peach Tree Borer Management; Replanting Weeping Cherry After Borers: Soil Treatment and Care; Apricot Borer Cleanup: Protecting Neighboring Fruit Trees; Sap Leaking at Cottonwood Base: Likely Borer Damage; Plum Tree Borers: Systemic Insecticide, Nematodes, and Tree Vigor; Eucalyptus Borers, Galls & Fungus: Systemic Insecticide + Fertilizer; Maple Borers: Low Spread Risk, Monitor and Protect; Managing Borers in Japanese Maples: Systemic Insecticides and Tree Health; Ash Tree Borer Treatment in Idaho: Can This Tree Be Saved?; Borers in Young Columnar Apple Tree: Can It Be Saved?

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