Common Tree Pests in Sonoma County and How to Identify and Manage Them

In 2018, California lost 18 million trees due to a combination of drought and pests. In years prior, these common infestations did not pose as big of a risk to Sonoma County trees. The environmental changes and prolonged periods of time without adequate water has left them increasingly vulnerable. 

To help ensure the trees on your property do not fall victim to unwanted guests, it is important to know how to identify and eradicate invasive insect species. In this guide, we outline the dangers of three of Sonoma County’s most common tree pests and how you can manage them.

1. How the Bark Beetle Is Killing Trees in Sonoma County

With recent drought throughout Northern California, the Bark Beetle has become one of the biggest threats to trees in North America. The beetles burrow into the bark of the tree and produce a fungus that interrupts the tree’s circulation of vital nutrients. When these insect pests successfully colonize a tree the likelihood of the tree surviving is low. 

Under normal circumstances, a tree’s natural defense forces the Bark Beetle out through “pitch-tubes”. These tubes are actually bubbles of sap the tree secretes to evict the insect from its bark. In cases where a tree is already in duress and a colony has taken over, even early-stage intervention with chemical treatments will not save it from this insect infestation. The tree will need to be removed by a professional to avoid further infection of nearby trees.

Signs of Bark Beetles on Your Trees

• Pitch tubes: reddish-brown or white bubbles on the outside of the bark
• White pitch tubes – sap bubbles – mean your tree was successful at protecting itself
• Reddish-brown pitch tubes indicate an active infestation
• Flaking bark or holes in tree bark
• An influx of forging wood-peckers and other birds
• Top-kill
• Yellow to brown foliage

How to Manage Trees with Bark Beetles

• Prevention is key: strong and healthy trees can defend themselves
• Insecticides
• Ground Sprays 
• Immediate infected tree removal

2. The Effects Of Oak Ambrosia Beetles on Sonoma County Agriculture

While Ambrosia beetles may look similar to bark beetles – 3-5mm long, reddish-brown or black – they are a very different specialized group of bark beetles. Ambrosia beetles excavate tunnels, referred to as “galleries” inside of stems and trunks of trees, but rather than residing just below the surface of the bark, they burrow deep into the sapwood. There, they do not feed on the tree, but on fungus that lives on the walls of their galleries. Normal healthy trees will typically irradicate an infestation through natural defenses. But if your tree is already in distress an Ambroise beetle infestation will be deadly.

Signs of Oak Ambrosia Beetles on Your Trees

• Toothpick shaped strands of sawdust pocking out of tree bark
• Sawdust accumulating around the base of the tree

How to Manage Your Tree With Oak Ambrosia Beetles

• Prevention is key: strong and healthy trees can defend themselves
• Immediate infected tree removal

3. The Gypsy Moth Pest and Sonoma County Trees

The Gypsy Moth’s larva feeds on the leaves of many trees native to Sonoma County and is largely responsible for mass defoliation throughout the county. One gypsy moth larva can eat up to one square foot of tree leaves per day. If this infestation is left untreated, it can leave your trees even more vulnerable to disease or other threats. Due to environmental stressors, the trees most at risk of dying from Gypsy Moth defoliation are those in urban areas.

Signs of Gypsy Moths

• Hairy teardrop-shaped egg masses
• Hairy brown or black caterpillars w/ red and blue spots
• Sudden defoliation in trees

How to Treat Trees With Gypsy Moth

• Gypsy Moth traps
• Gyspy Moth sprays
• Fogging techniques
• Ground sprays

Keep Your Sonoma County Trees Healthy With The Help of Vintage Tree Care

When it comes to keeping the trees on your property thriving the best tactic is prevention. We encourage all Sonoma County residents and business owners to check the trees on your property often and schedule routine trimming & pruning. Our skilled arborists at Vintage Tree Care will help ensure the health and longevity of your trees for years to come. Call us or contact us online for a professional risk assessment, or an Estimate.