Behind the Dogwood’s Bark

by Ray Novitske, Fairfax Master Gardener

damage on tree

damage from borer

What is a dogwood borer? A good answer might be “a borer that attacks our flowering dogwoods (Cornus florida).” The dogwood borer (Synanthedon scitula) is a native insect found in the Midwestern and Eastern United States, from Canada to Florida. As an adult, it is a small clearwing moth resembling a wasp, with a blackish blue and yellow banded body about 3/4 inch long. It is the borer’s larva stage that causes damage to our native trees.

This pest, named after the first plant it was found on, doesn’t limit itself to dogwoods. It will attack oak, mountain ash, birch, chestnut, willow and pecan trees as well. In the 1980s it was discovered infesting apple trees, too. Studies have indicated that on apples, the dogwood borer prefers the burr knot tissue where grafts try to grow new roots, especially on certain apple rootstocks. From there, it will find its way to other healthy tissue.

Usually the damage from the borer is not severe enough to kill the tree, but successive years of heavy damage could do just that. This is especially true if the tree is stressed by other factors, such as drought, physical damage or being in full sun. Dogwoods are an understory tree, meaning their native habitat is at the end of a forest under other tre