Things You'll Need
Pruning shears or loppers
Natural wood-boring beetle predators
Carbaryl or pyrethroid insecticide
Because cedar bark beetles are more likely to infest weakened or dying trees, practice proper cultural care of your cedars to keep them healthy. Proper watering, fertilizing and pruning of your cedar tree can help reduce or prevent wood-boring beetle infestations. If you live in a region where carbaryl and pyrethroid insecticides aren’t available for homeowner use, you may need to hire a licensed pesticide applicator to perform the bark beetle treatment on your cedar trees.
Beware that severe infestations of wood-boring beetles like the cedar bark beetle can require complete removal of the infested tree. If you see lots of tunnels in the trunk of your cedar tree, you may need to cut down and dispose of the tree altogether, because insecticides and pruning won’t likely work effectively enough to control the infestation.
The most common type of wood-boring beetle that attacks cedar trees is the bark beetle, belonging to Phloeosinus genus. The western cedar bark beetle of the species Phloeosinus punctatus is especially common in cedar trees. These wood-boring beetles are hard-bodied, reddish-brown to black and shiny, and about 1/10 inch or 2 to 3 millimeters in length--about the size of a grain of rice. You'll likely see tunnels on the cedar tree's wood surfaces and inner bark, along with eaten and dying or dead twigs. You can control wood-boring beetles on cedar trees using specific methods.
Prune away and destroy all branches and twigs on the cedar tree that are infested with or show symptoms of wood-boring beetles. If you're unsure about whether a particular tree limb is infested with the cedar bark beetles, you can pull off a small area of the bark to look for the boring tunnels in the wood.
Release natural predators and parasites of the cedar bark beetle onto and around the infested tree to control the beetle population. Parasitic wasps, snakeflies and certain types of predaceous beetles may help to reduce bark beetle populations. Woodpeckers also tend to feed on wood-boring beetles.
Apply an insecticidal spray to your cedar tree to kill the adult beetles when they land on the tree. Insecticides won't necessarily kill the eggs, larvae or adult bark beetles after they've bored into the tree, however. Thoroughly spray and drench the cedar tree, particularly the trunk and branches, with a pyrethroid insecticide or flowable formulation containing carbaryl, following the instructions on the label.
Set out pheromone traps in your landscape, away from your cedar trees. Bark beetles attract mates by releasing airborne pheromones, and these types of traps can help reduce the populations. Utilize the pheromone traps according to the manufacturer's recommendations.
Spray your cedar tree with carbaryl to prevent bark beetle infestations during spring through late summer, when adult beetle populations are present. Thoroughly treat all new green stems that are larger than 1 inch in diameter, along with the branches, trunk and other woody parts of the cedar tree, following the instructions on the pesticide label. This treatment is effective at preventing bark beetle infestations, not treating existing infestations.
Sarah Terry brings over 10 years of experience writing novels, business-to-business newsletters and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.