photo credit: Oregon Department of Agriculture
The Mediterranean Oak Borer Beetle (Xyleborus monographus) has been threatening
oaks in areas across Northern California.

The threat: Mediterranean Oak Borer beetles - shorthanded as MOB by Windsor parks chief Charlie Johnson.

"MOB is an ambrosia beetle native to the Mediterranean region," Johnson said. "It was first discovered in neighboring counties approximately five to 10 years ago. It creates its own food source that it creates inside the tree that contains a symbiotic ambrosia fungi."

"The main host trees for MOB are oak trees with Valley, Blue, Oregon, [and] White Oaks being the most common," Johnson said.

While the beetle does not target coast live oaks, its hit Valley and Blue oaks on town property hard, leaving 905 trees at high-to-moderate risk of infestation.

With the beetle on the march, Johnson said Windsor is leaning on a new treatment for the pest.

"I would stress, again that this is experimental for this type of beetle," Johnson said.

Emamectin benzoate, sold under the name Boxer, is the treatment in question.

It's an insecticide more commonly used to treat a different borer beetle, the Emerald Ash Borer.

Johnson said he and his colleagues with other local governments are trying to figure out how to guard against further spread of the invasive beetle.

"The County has actually reached out to us and they're kind of waiting to see what we're gonna do first before they act," Johnson said. "And then we've talked to other tree services over in Napa County, they've been injecting over there and having some success."

An arborist's report recommends injecting the Boxer insecticide into the vascular system of at-risks trees during the spring time to guard against the Borer beetle; with the report saying that, "taking no action at all will definitely not be effective and the infestation will spread."

Windsor has so far removed seven infected oaks, including five trees at the site of the first reported infestation on Conde Lane.