Citizen scientists, researchers using surveys to monitor invasive spongy moth populations in Ky.

University of Kentucky surveyors and citizen scientists are monitoring Kentucky forests in an effort to slow the spread of an invasive species of moth that could harm local foliage, hurt the state’s economy and make its woodlands less pleasant.

Efforts to track and limit the proliferation of spongy moths – formerly known as European gypsy moths – have been ongoing for more than four decades in Kentucky .

Carl Harper, one of the Senior Nursery Inspectors with the University of Kentucky and manager of the Citizens’ Science Program, referred to the invasive species, when in large quantities, as “destructive pests.”

“The caterpillars will feed on the leaves, and when that takes place, the trees do not have a way to photosynthesize, and they have sent out another flush of leaves. They can only do that so much before it really causes the trees to start deteriorating,” Harper said.

The bugs can also make woodlands less attractive for visitors. Contact with spongy moth caterpillars can cause skin reactions resulting in “itchy, raised welts that look like a blister can be very uncomfortable,” according to UK. Large populations can also “produce untold amounts of fecal material.”

“Residents of the northeast report that it sounds like continual rain as the droppings fall to the forest floor and that the annoyance can drive people away from parks and recreational areas,” according to UK’s Department of Entomology .

The species is of particular concern for the state’s bourbon industry – which the Kentucky Distillers Association estimates had a $9 billion economic impact in 2023 . Makers of the state’s signature spirit generally age their product in barrels made from white oak trees. Many industry experts have claimed for years that a shortage of the trees is on the horizon , but a growing population of spongy moths – whose primary host is the white oak – could present a major threat.

Though hundreds of specimens have been captured in eastern Kentucky in recent years, no established populations of the invasive species have been identified in the state.

Historically, the species was brought over to Massachusetts from Europe over a century ago to aid in silk production. Some caterpillars were inadvertently released into the surrounding forests and, by 1922 , the invasive species had spread throughout the state. Over the course of decades, the species spread to surrounding states and spread to the west and south.

Slow the Spread , a forest health protection project with the United States Forest Service, charts the spread of spongy moths in the U.S. According to the organization’s maps, far eastern Kentucky is located in an action zone – meaning surveyors in the state trap and eradicate the invasive species. Bordering states, including Virginia, West Virginia and Ohio, have been labeled as monitoring zones where researchers can study established populations.

The Citizens’ Science Project , a public program through the University of Kentucky, allows volunteers to aid in researching invasive species, like the spongy moth.

“We as humans are good at carrying pests from one place to another, but we can be good at stopping it as well,” Harper said. “We're trying to let the general public know about these pests because every eye that is out there can look for it will help us mitigate the spread of this, you know, of invasives.”

Harper added that much of the program’s trapping efforts are focused in eastern Kentucky, but that a rotation of western Kentucky sites – including the region around the Land Between the Lakes National Recreation Area – are regularly monitored.

Ryan Drake, an independent contractor with UK, currently surveys the forests near LBL. He says every time he opens a trap he’s hoping to find it empty.

“You know, I hope [Eastern Kentucky] is containing them,” Drake said. “I hope they’re not getting to western Kentucky, and we don’t have a big boom or outbreak of them.”

Drake, who owns a logging company in central Kentucky, remembers conducting surveys to monitor the spread of the Emerald Ash Borer , another invasive species present in the state. Though surveys for its spread have ceased, he said large quantities of ash forests cannot be treated any longer and that could result in a future where the Commonwealth can’t harvest native ash wood.

He hopes a similar fate doesn’t befall Kentucky with spongy moths, which he said could be detrimental to the timber industry in the state for decades to come.

“Up in the northeast, the moths have killed forests when they’re not treated,” Drake said. “So it’s one more thing to worry about.”
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