Beware of Lanternflies—This Spotted Bug is a New Invasive Garden Pest

These moth-like insects are bad news.

As bugs go, spotted lanternflies look striking. This black-spotted bug is pale gray with crimson-tinged wings with geometric lines. But pretty as these moth-like insects are, it's bad news if you find one. Spotted lanternflies are a newer pest currently found in 14 northeastern states. They're devouring vineyards, munching on specific trees, and delaying shipments of everything from lumber to milk.

Lanternflies are a nuisance for homeowners and gardeners because they eat more than 70 species of edible and ornamental plants. They make a mess by leaving droppings everywhere and excreting a sticky substance called honeydew, which causes a black mold to grow on plants.

spotted lanternfly on maple tree
arlutz73 / Getty Images

Why Are Lanternflies Bad?

Spotted lanternflies are an invasive insect pest from China. "They're a bad bug," says Dr. Kelli Hoover, Professor of Entomology at Penn State University. Lanternflies were first discovered in the United States in 2014 in Pennsylvania. Hoover says they likely hitched a ride on a shipment of stones from Asia. A study from Penn State estimates that spotted lanternfly damage could cost agricultural industries nearly $100 million in Pennsylvania alone.

However, the cicada-sized insects are currently found in 13 other states: Connecticut, Delaware, Indiana, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Rhode Island, Virginia, and West Virginia.

Bad News for Crops and Gardens

spotted lanternflies laying eggs on a tree
Spotted lanternflies lay eggs in small grayish masses that look like a smear of dried mud. Courtesy of Penn State

Unfortunately, the pests will likely continue to spread because they're good at it. Lanternflies can lay eggs on anything from an RV bumper, to rocks, to lumber, so they're masters at hitching a ride to new areas. In addition, they have a long (for a bug) lifespan of six months, can survive cold winters in their egg stage, and appear to have no natural predators. "They're going to be with us awhile," Hoover says.

Lanternflies are the hardest on vineyards. They kill grapevines by sucking the sap out of them, stealing the source of energy the plants need to survive the winter. Lanternflies also destroy hops fields, which is bad news for beer brewers. They do heavy damage to home-gardening favorites such as cucumbers, strawberries, raspberries, and roses. "There's very little they don't eat," says Hoover.

How to Control Spotted Lanternflies

What should you do if you see spotted lanternflies flitting about your yard? "Stomp on them," Hoover says. Incredibly, that is the official advice for lanternfly control offered by experts across the lanternfly-invasion zone. "Join the battle, beat the bug! Stomp it out!" is the official slogan from the state of New Jersey for the lanternfly battle.

There are too many lanternflies to spray pesticide on all of them without making food crops inedible and killing beneficial bugs, Hoover cautions. "Lanternflies move in massive flights, swarms containing tens of thousands of bugs," she says, noting that growers will "spray them in a vineyard and kill a bunch, but they just keep coming."

Hoover admits we won't solve the problem with our feet. "Stomping on lanternflies kills them, of course, but it doesn't have a big impact on their overall population," she says. But for now, it's at least something. "Since the lanternfly goes through six life stages, you have to tackle each stage differently," Hoover says. "We don't have a silver bullet."

Much of the eradication effort focuses on preventing lanternflies from spreading. The USDA is training dogs who can sniff lanternfly eggs on cargo. Businesses that ship everything from Christmas trees to nursery plants to milk tanks must double-check shipments for lanternfly stowaways.

The egg stage is when this spotted bug is easiest to control. If you find lanternfly eggs on plants in your yard, car, or home, scrape them off and put them in a container of rubbing alcohol to kill them. The eggs look like small, gray, putty-like masses about an inch long.

If you see lanternfly nymphs and adults, it's stomping time. Just don't expect the bugs to make it easy. They can leap 20 feet in the air to escape. "If you approach them from the front, they seem to be easier to get," says Hoover. "It's like they can't see you as clearly as when you approach from behind."

Silver Linings and Possible Solutions

While all this can sound a bit apocalyptic, the news isn't all bad. Spotted lanternflies aren't the worst invasive bug ever to reach our shores. For example, they're not as destructive as bark beetles, which attack native trees and threaten to wipe out entire forests in North America. The only tree that lanternflies kill outright is the tree of heaven (Ailanthus), an invasive plant from the bugs' Asian homeland.

"Other than grapevines, lanternflies are not killing plants we want," Hoover says. "They're merely stressors on other plants." Luckily, you can save your plants after lanternflies damage them. First, smash the insects, then water your plants to make up for the sap sucked out of them.

Hoover is hopeful that nature may hold a solution to the infestation. "I suspect over time, we'll have native, natural enemies that will eat spotted lanternflies," she says. "But we're not there yet."

After birds were seen snapping up spotted lanternflies and spitting them out instead of eating them, Penn State researchers discovered that the bugs taste bad. "They take toxins from tree of heaven and black walnut trees and store them in their body," Hoover says. "It makes them taste bitter as a deterrent to predators."

Hoover says maybe predators such as spiders or assassin bugs will step up and put a dent in the spotted lanternfly population. Until then, keep on stomping.

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