What’s Killing the Ash Trees?

By Lauren Woodard

If you live in one of over 20 states impacted so far by the emerald ash borer you may have experienced firsthand the destruction left in this invasive insect’s wake.

These half-inch interlopers are steadily killing our native ash trees, and the devastation reaching from the Midwest to Pennsylvania and northward is now “inevitable,” says Academy Curator of Entomology Dr. Jon Gelhaus.

The emerald ash borer, Agrilus planipennis, already has killed millions of ash trees since its arrival from Asia a little more than a decade ago. Creating S-shaped tracks beneath the ash tree’s bark, the beetle’s larvae kill the tree from the inside out.

Gelhaus notes the movement of the emerald ash borer has been fast, with recent movement in the last two years to Montgomery and Bucks counties in our area and a report last month that the beetle has reached New Jersey.

The options for dealing with the ash borer are expensive; either treat the trees with preemptive and continual pesticides or pay to have the trees removed later. There are no methods of borer containment, and releasing of natural predators (biological controls) is still in the testing phase.

The emerald ash borer, or Agrilus planipennis, is a pesky kind of beetle that destroys trees using its larvae. Photo: U.S. Department of Agriculture.

Gelhaus ties the unintentional transplantation of the emerald ash borer to movement of cargo containing infested wood, probably by ship, trains, or planes. Dead trees already affected by the insect also are an issue.

“People cut up the dead tree, transport it as firewood, and then they store it. The beetles emerge, and we’ve infested a whole new area,” he explained. While the public cannot put a permanent stop to the crusade against the ash trees, citizens are able to be proactive in the face of invasion.

“People can help by learning what our ash trees look like, going outside in their yard and neighborhoods, and detecting trees that are dying,” Gelhaus said. “You can treat your trees, but it’s not an easy solution.”

It is important to know the signs of the emerald ash borer’s presence. Eggs laid on the outside of the ash tree become larvae that burrow through the tree bark to grow and exit as adults. The insect’s exit holes are shaped like the letter “D” and are visible in the side of the diseased tree.

Less minute signs of damage can be found by looking at the tree’s top branches; dying begins there first.

“Be aware that these are serious things,” Gelhaus warns. “Try to identify the trees in your yard. Which ones are ash trees? Look and see what the health of those trees are.”

For tech-savvy individuals, Gelhaus recommends two smart phone apps. TreeSnap helps the public identify trees, while Bugguide, an app used by scientists at the Academy, is useful for looking up related insect species. Other useful information about the emerald ash borer can be found by visiting these sites:

-Pennsylvania Department of Agriculture and local extension offices

-New Jersey Department of Environmental Protection website

The Academy is home to nearly 4 million insect specimens, including its collection of emerald ash borers. The Academy’s insect specimens will be on view at its annual Bug Fest, taking place Saturday and Sunday, Aug. 12 and 13. Stop by the Academy and make critter-themed crafts, watch a live invertebrate stage show, meet a bedbug sniffing dog, talk about insects with real scientists, and more.

Also learn about backyard biodiversity and the interactions between insects and plants inside Backyard Adventures, the special exhibit view through Sep. 10.

To purchase tickets at a discount for Bug Fest and Backyard Adventures, click the button below:

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