How Do Emerald Ash Borers Kill Trees?

Emerald ash borers (EAB) are small, metallic green beetles that have caused widespread destruction of ash trees across North America. These insects are originally from Asia and were first discovered in the United States in 2002. Since their discovery, they have rapidly spread, killing millions of ash trees. Southern Star Tree is a professional tree care company that’s dedicated to helping property owners understand how these pests kill trees, and provide effective management solutions to prevent devastating damages. Let’s explore the mechanisms by which emerald ash borers cause such extensive damage to help you make informed decisions.

Egg-Laying

The process starts when adult female emerald ash borers lay their eggs in the cracks of ash tree bark. These eggs are almost invisible to the naked eye, hence the need to schedule routine inspections with a professional tree care company to mitigate the devastating cycle. After about a week or two, the eggs hatch into larvae, which are the real culprits behind deterioration and tree removal emergencies. These larvae burrow into the tree to access the nutritious inner bark, or phloem.

Larvae Feeding on the Phloem

Once inside the tree, the larvae feed on the phloem, the layer of tissue responsible for transporting nutrients and water throughout the tree. The phloem is essentially the tree’s circulatory system, and as the larvae chew through it, they create winding, S-shaped channels. This disrupts the flow of nutrients and water, slowly starving the tree. The more larvae present, the more extensive the damage, and eventually, tree removal.

Disruption of the Tree’s Vascular System

As stated, larvae consume the phloem and damage the layer beneath the bark and produce fresh growth. As the larvae continue to feed and grow, they effectively girdle the tree, cutting off its ability to transport life-sustaining resources. This disruption causes a gradual decline in the tree’s health, often resulting in wilting leaves, thinning canopy, and eventually, the death within a few years. If you notice telltale signs of deterioration, call certified tree service professionals to diagnose and address the problem early.

Weak Defense Mechanisms

Ash trees have natural defense mechanisms to combat pests, such as producing chemicals that can deter or kill insects. However, the number of larvae and the rapid pace at which they invade can be overwhelm the defenses. In addition, larvae make it hard for the tree to defend itself, creating a vicious cycle where the tree’s declining health allows for more extensive damage. Fortunately, certified arborists can prevent such scenarios by implementing preventive measures to maintain optimum health.

Adult Beetles Emerge and Continue the Cycle

After several weeks of feeding, the larvae mature into pupae and eventually transform into adult beetles. These adult beetles then bore their way out of the tree, leaving distinctive D-shaped exit holes in the bark. Once free, they fly off to nearby ash trees, where the cycle begins anew. Each generation of emerald ash borers can cause significant damage, and with multiple generations possible in a single year, routine care by trusted tree service professionals can prevent the spread of these pests.

Emerald ash borers are a formidable enemy to ash trees, feeding, girdling, and overwhelming these majestic plants. The key to preventing widespread devastation lies in early detection, effective management, and, where possible, protecting ash trees through chemical treatments or biological control measures. Contact us at Southern Star Tree and schedule a consultation with our certified arborists to combat this invasive species and preserve your ash trees for future generations.