CBT has become quite the nuisance in the North West. It made its appearance in tortix mothRichmond BC in 1989 and was seen in Washington as early as 1991. A 1996 survey of randomly selected cherry trees in Bellingham, showed 75-80% of the trees were found to be infested with CBT. Currently, the Seattle area is experiencing these same infestation rates. The most damaging stage for these moths is the 2nd through the 5th Instars. These boring Lepidoptera will tunnel between the bark and cambium, but do not penetrate the hard wood. Infestations usually occur upward from the base of the tree. Infestations are easily recognized by reddish-orange colored frass accumulations or frass tubes near gallery entrances. Larvae damage trees by direct feeding which reduces or excludes transportation of nutrients to the roots. The feeding causesexudation of gum and deformation of bark growth on the main branches and trunk. Along infested sides of the tree, die back of new and old growth can occur from the portion girdles. Indirect damage occurs through the formation of habitats for secondary pests such as bark beetles, fungi, and increasing susceptibility of infested trees to successive years of freezing damage, which can result in the death of the tree.
Treatment for these pests has proven to be difficult. The only opportunity for control is to spray when the egg sacks hatch between mid-September to October. Once they are in the tree there is no control for them, so timing is imperative. If you have any questions about this pest or think you might have damage. Contact Washington Tree & Lawn Care for a free estimate.