Blue Ridge

By Julie Reardon

Losing the Battle of the Beetles

Ash trees are losing the “battle of the beetles” and dying out in Virginia. We said good bye to some old friends this spring as we took down a dozen dead and dying trees lining our drive and shading our house and barns. Although we’ve lost dozens of ash trees here on our farm, the ones lining our drive were massive and took the longest to die. Both here in Fauquier County and throughout the state, the dead and dying trees are victims of an invasive species from Asia by way of China, the emerald ash borer beetle (EAB). Not as well-known but equally despised, it arrived in our country about the same time as the brown marmorated stink bug. The EAB joins the stink bug, snake head fish, ailanthus tree, kudzu and a host of other invasive species as a major disruption to our ecosystem, the total effects of which are not yet known. First seen in Michigan in 2002, the EAB hitch hiked to this country most likely on hardwood packing material on airplanes or cargo ships.

Since then, the killing swath has spread to nearly 30 states including Virginia, West Virginia, North Carolina and Tennessee, killing tens of millions of ash trees.  The four most common varieties of this tree in our area, including the forests in the national parks and in the cities and towns, are all members of the fraxinus species. All are vulnerable to the destruction caused by the beetle.

And the beetle is sneaky. Once it arrives, the EAB may take two or three or even four years to kill a big healthy tree. They eat the leaves but the real damage is done when the females lay eggs under the bark. The larvae then tunnel in and feast on the tree’s inner bark, hindering the flow of water and nutrients and ultimately girdling and killing the tree. The first signs can be easy to miss: dead foliage in the upper canopy, woodpecker holes as they seek out the grubs. By the time there is obvious damage, such as multiple dead branches and bark sloughing off, the damage has been done and death is imminent. It’s almost impossible to notice any visible damage until it’s too late.

The National Park Service estimates that close to 50 percent of the ash trees in Virginia’s section of the National Capital Region have been lost since 2013; with numbers much higher in some areas. Between 2013 and 2017, an estimated 40 percent of the ash trees along the George Washington National Parkway died. Although research is ongoing for control of the EAB by using non-stinging predator wasps, treatments that kill the larvae are too risky to beneficial insects and animals. And the EAB has no natural predators here. But it’s not just our national parks and wooded areas of the countryside that are suffering the impact. Decades ago, these tall, stately shade trees were planted by the thousands in cities like Richmond, Alexandria and Washington D.C. because of their affinity to our area, their durability, fast growth and beauty. It’s an adaptable tree that until now, thrived in upland as well as important wetland habitat and under a variety of conditions; the same qualities that made them ubiquitous in forested areas made them an ideal choice for urban areas, too. But because it is so large (most grow over 100 feet), it can do considerable damage to homes, buildings and wiring when it dies. And like any large tree in tight quarters, it requires skill and equipment to take down; the expertise to do it properly is expensive. Removing the dead and diseased ash trees poses unique public works challenges because they pose such a risk to life and property in densely populated areas. Unlike a single tree that falls in a forest, a single tree in a city or suburb can fall on a house, car or power line, or even a person.

Less obvious but more troubling is the ripple effect that the disappearance of an entire species may have across the Commonwealth. The ash is considered a foundation species. They often prefer to grow along stream banks and in wetlands, and play a key role in soil stabilization and erosion prevention, particularly important to policymakers in the Chesapeake Bay watershed area to meet water quality goals. Scientists agree that losing important trees can change the entire geomorphology of an area and have a ripple effect through the entire ecosystem. Losing a key species will cause changes in both flora and fauna. The first to die off will be insect species; as they die or find new habitat, the bird species that rely on them will also shift; decreased tree canopy will let more light reach wetland waters and that will affect fish and other aquatic species as well as the forest floor. An open wetland with big trees can change almost overnight to something very dense and shrubby. And while it’s too early to say such a change would be detrimental overall, it will be different and likely result in an uptick of more non-native plants that will out-compete the natives and fill the void.

A native of Southeast Asia, the EAB is merely a nuisance over there and is typically found in much lower densities since unlike over here, it has natural predators that keep it in check. It can only travel about a half mile from the tree it emerges from, but here in the U.S., it’s spread further by people transporting infested firewood, nursery trees or logs to non-infested areas. As an invasive species here in the U.S., they are now considered the most destructive forest pest ever seen in North America.

If you currently have ash trees on your property and they are looking a little destressed, you might want to have them checked to see if they could be losing the “battle of the beetles” like ours did.

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