The Two-Lined Chestnut Borer (Agrilus bilineatus) is native to North America, and to date can be found throughout eastern United States, south to Georgia and Texas, and west to the Rocky Mountains, as well as parts of south and eastern Canada. Two-lined Chestnut Borer (TLCB) was given the name “chestnut” borer because it was a primary pest of the American Chestnut tree. Since then, the American Chestnut has been almost completely wiped out by a fungal disease, yet the insect has retained its name despite the fact that there are few Chestnut trees for it to attack. While it will still attack Chestnut trees when present, the primary host for TLCB these days is Oak trees, and is considered one of the most serious insect pests affecting Oaks. 

The adult insects are slender and about ⅕-½” long, have a bluish black hue, and have two thin stripes down its wings. The larvae are white, thin and about 1 ¼” long (when fully grown,) have an enlarged head and two spines at the tip of their abdomens. Adult beetles cause relatively little damage, but the larvae feed on the xylem layer and disrupt the movement of water and minerals within the tree. The insects are rarely seen, and therefore an active infestation is often identified by visual changes in the tree itself.