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All About Borers in Northern CA

Battling Borers: Protecting Northern California’s Trees

Northern California’s scenic landscapes boast diverse tree species, but lurking within are borers—tiny insects capable of inflicting severe damage. In this guide, we’ll explore common borers in the region and strategies to safeguard your trees.

Common Borers:

Bronze Birch Borers: Bronze birch borers are tiny beetles that harm birch trees by boring into their wood. This damages the tree’s vascular system and weakens it. Signs of infestation include yellowing leaves and branch dieback.


Elm Beetles: Elm bark beetles are small insects that invade elm trees, especially when the trees are weakened. They bore into the bark and lay eggs. Their larvae feed on the inner bark, disrupting the tree’s nutrients and water flow. This can cause the tree to decline or die. Elm bark beetles also spread Dutch elm disease, a fungal infection harmful to elms.

Olive Bark Beetles: Olive bark beetles are tiny insects that attack olive trees, burrowing into their bark and causing damage. They lay eggs in the tree’s inner layers, leading to larval feeding that weakens the tree. Infestations can result in wilting leaves, branch dieback, and tree decline. Control measures include pruning affected branches and applying insecticides to manage beetle populations.

Sycamore Borers: Sycamore borers are small beetles that pose a threat to both sycamore and oak trees. They tunnel into the wood, laying eggs and causing damage to the tree’s structure. This infestation weakens the tree and can lead to branch dieback.

Turpentine Beetles: Turpentine beetles are small insects known for infesting pine trees. They bore into the tree’s bark and create galleries where they lay eggs. Larvae feed on the inner bark, disrupting the tree’s nutrient flow and causing damage. Signs of infestation include pitch tubes on the tree’s trunk and canopy dieback.

Protection Strategies:

Regular Inspection: Monitor trees for signs of borer infestation, especially during peak activity periods.

Pruning and Sanitation: Remove infested branches promptly to prevent borer spread.

Maintain Tree Health: Ensure proper soil moisture and address stressors to keep trees resilient.

Chemical Treatments: Consider insecticides for borer control, applied following safety precautions and instructions.

Borers pose a significant threat to Northern California’s trees, but proactive measures can mitigate their impact. By staying vigilant and employing effective protection strategies, you can preserve the health and beauty of your trees for generations to come. If unsure, consult local experts for tailored guidance on borer management.

Our Tree, Shrub, & Ground Cover Program includes treatments for some of these pests.

If you think you’re seeing signs of borers on your property please reach out to us!

Phone (Call or Text): (925) 676-6021

Email: [email protected]

Or visit our sister website at Gopher Team to submit an online submission!