CHATSWORTH : Beetles, Squirrels Pestering Oak Trees

Chatsworth’s oak trees, under severe stress from the years of drought and increasing air pollution, must wait until spring for relief from a plague of bark-boring “twig girdler” beetles that are slowly killing the trees, city officials said.

In September, the Los Angeles Department of Water and Power got involved in efforts to save Chatsworth’s oak trees, many of them hundreds of years old, after residents noticed that many of the trees appeared to be dying. About 60 California live oaks and California valley oaks can be found in the Chatsworth Reservoir, which is owned by DWP.

Oak trees are viewed as a precious ecological resource and are protected under city and county ordinances.

DWP officials held a town meeting last month with residents to discuss the possibility of spraying a pesticide that would eliminate the beetles.

“Some residents had concerns about the spraying,” said Mindy Berman, a DWP spokesman. “So we’ve decided to hold off for now. The bug is going into its dormant phase, so spraying now would be ineffective. We’ll have to wait until the spring. In May, we’ll have to take a comprehensive look at the situation and decide what to do.”

Residents also asked the department to consult with independent arborists before taking action.

Berman said the department’s horticultural experts are hoping for a wet winter, which would increase the trees’ strength and ability to resist the bark-eating bugs that lay their eggs in the bark. When the eggs hatch, the beetles eat their way out of the tree.

In the meantime, the DWP will continue filling ground squirrels’ burrows around the “dead zone,” an area six feet in diameter beneath the trees. The squirrels are also partly responsible for the sad condition of the oaks, which had clusters of dead, brown leaves and branches well before autumn.

“We’re going to do what we can; we’re definitely concerned,” Berman said. “Those oaks are older than all of us put together.”