Drought and the Bark Beetle in Southern California

Bark beetles.  They are a big problem here in the Inland Empire and the  High Desert for our pines and conifers There are bark beetles that attack pines, arborvitae, cypress, false cypress, junipers, and redwoods and many others). California has over 20 varieties of bark beetles. In years past, our mountain communities of Big Bear, Lake Arrowhead and Wrightwood have been hit hard. There has been a big push in the last few years to cut down the stricken trees to minimize the spread to other trees and the fire potential.

We thought we had crossed the safety mark a few years back and had turned the tide towards getting a handle on them after mass removals of the dead trees. The current drought conditions are making us rethink that as the bark beetles are back with a vengeance due to insufficient water to our trees.

The bark beetle adults are small, hard-bodied insects about the size of a grain of rice and most are dark red, brown, or black. Look for a pattern like buckshot on the bark surface of infested branches or trunks where the new adults have emerged. The adults tunnel through the bark  and lay eggs under the bark. The eggs hatch and become larvae that tunnel through the inner bark, where they overwinter, creating large galleries of tunnels where they disrupt the  flow of water and nutrients to the tree resulting in dead or dying branches and eventually the entire tree.

The larvae then emerge from the tree as flying adults and they look for new trees to infest resulting in a ruthless cycle of death. Their favored target is a tree that is stressed by drought, improper planting, improper pruning  or other conditions.

Because the beetles live in the protected space under the bark, it is very difficult or sometimes impossible to obtain control once the tree is infested. Timing is all important when making applications to prevent infestation.

Prevention is the best way to combat these beetles with proper maintenance and watering. Most people do not water their trees well.  They start with one or two little emitters that put out a gallon of water each when ran for an hour, and then they cut down the watering schedule to 10 or 15 minutes a day thinking the trees should be watered the same as a spray system for your lawn. (Hey that’s not right for your lawn either, but that’s another article). 15 minutes with a 1 gallon per hour emitter is 32 ounces.  Not very much except for the tiniest of trees.

As the tree grows, it will require a lot more water. A typical tree with a 15 -20 foot spread can use as much as 50 gallons of water a day. BUT you should not water every day either. The best way to water trees is to water infrequently, perhaps 2-3 times a week in summer.  Water deeply when you do water so that the soil is wet down at least 12 -14 inches.  Depth and frequency will depend on tree type. soil type and weather.

A key component of prevention is to provide proper maintenance and have a licensed pest applicator apply a systemic insecticide to prevent  the beetles from getting established. Systemic insecticides are taken in by the tree’s vascular system and distributed throughout the tree so that when a beetle bores into the tree trunk to lay it’s eggs, it is killed by the insecticide, thus preventing it from laying eggs that will hatch into the larvae that will kill the tree. There are many methods of application for the insecticides.

Give us a call. We are licensed pest control applicators and we are experienced to help you with your tree pest issues.

(760) 868-6104