The emerald ash borer (EAB), an invasive beetle responsible for the destruction of millions of ash trees across North America, continues to pose a growing risk to Colorado’s urban and community forests. EAB primarily attacks ash trees (genus Fraxinus), laying eggs under the bark. When larvae hatch, they feed on the tree’s inner tissues, disrupting the flow of water and nutrients and eventually killing the tree. According to the Colorado State Forest Service (CSFS), an estimated 15 percent or more of all urban and community trees in Colorado are ash species, making neighborhoods particularly vulnerable if no action is taken.
Recognizing the Signs
Early detection of EAB can be difficult, especially for untrained observers. Common warning signs include thinning leaves in the upper canopy, vertical splits in the bark that may reveal distinctive S-shaped galleries underneath, unusually small leaves late in the summer, and new sprouts emerging along branches or within the canopy as the tree attempts to compensate for damage. By the time these symptoms are clearly visible, infestations are often well established…