It is hard to believe that something seemingly insignificant, like a beetle, could kill a fully grown tree. Typically, the main culprit of tree destruction is humans and natural phenomena, like lightning. However, there is a bullet-shaped, strikingly metallic beetle whose larvae are taking down ash trees from the inside: The Emerald Ash Borer (EAB).
First discovered in Missouri in 2008, these invasive beetles were never meant to be in the United States. According to Collin Wamsley, a state entomologist for the Missouri Department of Agriculture, EAB are native to Asia where ash trees have natural defenses against the larvae and are unaffected by their presence. In the U.S., however, the ash trees never developed an immunity to the larvae, which allowed the beetles to tear through native forests. Found in 35 states, the beetles’ larvae feed on the inner bark of ash trees and essentially choke it from accessing water and nutrients.
The larvae of the verdant green beetle have killed more than 50 million ash trees in the northern U.S., according to Missouri State Parks. The same study also found that in Missouri alone, ash trees make up around 14% of trees that line the streets in communities as well as over 21% of the trees in urban parks. Wamsley and Kevin Rice, an assistant professor in the Division of Plant Sciences at the University of Missouri, explain that ash trees are also commonly used to make baseball bats and furniture. Not only are EAB taking away a great economic commodity, but they are also depriving communities of beautiful landscapes. If this destruction continues at this rate, it could contribute to there being less space for native species and more opportunities for invasive species.
When trees die rapidly in a concentrated area, they leave gaps in the canopy, which allows sunlight to hit the ground directly. This encourages invasive species’ populations to explode, Rice explained. The excess light can kill native plants that are not used to the harsh rays and provide a space for invasives to take over and outgrow native plants and trees. Some existing toxic plants can become even more toxic when exposed to excessive light, which can cause plants to grow more slowly and therefore become more vulnerable.
Fighting to minimize the harm of these beetles is difficult, but not impossible. People are taking action to help suppress and even kill off these invasive pests. This manifests in the quarantine of lumber found in infestation sites, biological practices and the work of people like Kevin Grieb, a graduate student at the University of Missouri, who does field work at infestation sites, for example, setting up traps to contain the beetles.