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The spotted lanternfly can ruin crops. It’s invading Loudoun County.

The invasive insects are not poisonous and do not bite humans, but they excrete honeydew that can devastate fruit crops and kill grapevines

The spotted lanternfly excretes honeydew, a sugar-rich waste product. (Mike Raupp/FTWP)
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The spotted lanternfly — an insect that can devastate large swaths of fruit crops — has arrived in Loudoun County this summer.

The insects are not venomous and do not bite humans, but they excrete a sugar-rich, sticky liquid known as honeydew from their backside. The honeydew promotes the growth of black, sooty mold, which can coat plants and prevent sunlight from reaching their leaves, reducing photosynthesis.

The honeydew falls from infested trees like a gentle rain shower, coating foliage, fruit, cars and lawn furniture, creating a mess to clean up, as well. The sweet liquid attracts yellow jackets, wasps and ants.

The planthopper was thought to be accidentally imported to Berks County, Pa., in 2014, presumably in a shipping container from Asia. Since then, lanternflies have spread across the Mid-Atlantic and have appeared in several counties in the Northeast and Midwest. Before the Loudoun County discovery, nearby quarantine areas were already established to stop the spread.

“Honeydew fouls foliage and fruit. The fruit becomes unmarketable, thus presenting a huge economic problem for growers of apples, cherries, peaches and grapes,” said Michael Raupp, an entomology professor emeritus at the University of Maryland.

The invasive spotted lantern fly is spreading across the Mid-Atlantic

Although the spotted lanternfly doesn’t kill most trees, it can kill grapevines. And if the vines survive, the grapes are tainted with the insect’s honeydew and can’t be used for winemaking.

The beekeeping industry is also affected. Bees that feed on honeydew produce a dark honey with an earthy or smoky flavor.

“I’ve tasted honey from bees that fed on honeydew, and it’s not something I want to put on my cereal,” said Brian Eshenaur, senior extension associate at Cornell University’s New York State Integrated Pest Management Program. But it is good for cooking, Eshenaur noted.

Eshenaur created the spotted lanternfly distribution map (above), and he updates it multiple times a year as the infestation expands. The spread of the lanternfly has occurred rapidly over recent years, he said, mainly because the insect is a good hitchhiker.

“On their own, spotted lanternflies can only fly up to five miles,” Eshenaur said. He recalls one infestation that was believed to occur when a horse farm relocated from New Jersey to Indiana, transporting lanternflies or lanternfly eggs across multiple state lines.

Paula Shrewsbury, an associate professor of entomology at the University of Maryland, teamed up with Raupp to trap lanternflies for a collaborative research project with the Agriculture Department’s Animal and Plant Health Inspection Service. Insect-killing fungus is being tested as a solution to reduce spotted lanternfly populations. The goal is to find biologically based insecticides.

Shrewsbury said hundreds of the sap-sucking insects cover trees within their study area.

“When you are standing under a tree that has spotted lanternflies, you feel tiny drops hitting your skin and think: Is it raining? And then you remember it is just spotted lanternflies in the trees peeing on you,” she said.

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The lanternfly’s honeydew coats everything under the infested trees. The combination of sticky honeydew and black, sooty mold makes an unsightly mess challenging to remove.

Shrewsbury mentioned that the spotted lanternfly’s honeydew has no odor, but Raupp recently tasted honeydew while trapping the bug. “It is mildly sweet, and I fully understand why ants, yellow jackets, honeybees, paper wasps and so many other sugar-seekers are attracted to it,” Raupp said.

The story of manna from heaven may have originated from honeydew excreted by sap-sucking insects, Raupp said.

The lanternfly’s preferred host is the Ailanthus altissima, known as the tree of heaven, but it will quickly move into wooded and residential areas to feed on other types of trees, such as maples or willows.

Adults lay eggs from September through December. Egg masses hold about 30 to 50 eggs and are approximately one inch in size, resembling dried mud. Females can lay up to two egg masses, typically on flat surfaces, including tree bark, rocks, lawn furniture or anything left outdoors. Although the adults don’t survive through the winter, the eggs can.

If you encounter the spotted lanternfly, you’re encouraged to squish it. You should also report any spotted lanternflies or egg masses to Maryland or Virginia Departments of Agriculture.