Spotted lanternfly experts debunk myths about the prodigious, pestilent pest

Amy Duke
January 20, 2021

UNIVERSITY PARK, Pa. — As the spotted lanternfly extension associate in Penn State’s College of Agricultural Sciences, Heather Leach often receives calls and emails from concerned citizens about the insect interloper.

Occasionally, she will hear stories or “myths” from them about management or the biology of the pest, an invasive planthopper that feeds on more than 70 species of plants, including agricultural and hardwood commodities.

“People who are dealing with spotted lanternfly are frustrated and worried,” Leach said. “In their search for answers, they sometimes are willing to believe or try anything. But it’s never a good idea to take questionable information at face value.”

While most falsehoods are innocuous, some have the potential to cause harm to the environment, animals and even humans. Below are a few garden-variety myths about the spotted lanternfly from Leach and her colleagues.

Pressure washing destroys spotted lanternfly eggs. While pressure washing might physically remove egg masses from surfaces, there is no evidence that it kills eggs. Additionally, high-pressure sprays can cause permanent damage to trees and other living plants.

The most effective way to destroy egg masses is to scrape them off using a plastic card or putty knife. Then, place the masses into a bag or container with rubbing alcohol or hand sanitizer, which can be disposed of in the trash. They also can be smashed or burned.

Milkweed is toxic to spotted lanternfly. According to Penn State Extension educators, milkweed leaves contain cardiac glycosides. These compounds affect heart function, making them toxic to most species of birds and mammals, so these predators avoid them. However, there is no science currently showing that milkweed is poisonous to the spotted lanternfly, Leach said.

On a positive note, milkweed is the sole host plant of the monarch butterfly. By planting milkweed species native to their region, property owners can support this important pollinator. But they should not expect to milk any benefit related to the spotted lanternfly.

The spotted lanternfly needs tree of heaven to reproduce. It does not, according to Kelli Hoover, professor of entomology, whose lab researched the insect’s reproduction cycle. She said while Ailanthus altissima, a noxious and invasive weed tree commonly known as tree of heaven, is the pest’s preferred host, spotted lanternfly can produce offspring without it.

“We reared spotted lanternflies from egg to adult — and they reproduced — without ever having access to tree of heaven,” said Hoover, adding that the specimens were fed a diet of planted silver maple, willow and river birch trees in a controlled outdoor setting.

Interestingly, development from egg to adult was slightly faster when spotted lanternflies were given tree of heaven, suggesting that it is a good host for them. Because tree of heaven is attractive to spotted lanternfly, Hoover recommends removing it, if affordable and feasible.

Homemade sprays are safe and effective. Folks may be tempted to use home remedies that include household items such as dish soap, glass cleaner, vinegar, salt, garlic and chili/cayenne peppers.

These suggestions may have the potential to harm humans, pets and plants, do not come with precise directions, may not be effective, and their use can violate the law, noted Emelie Swackhamer, a horticulture extension educator based in Montgomery Country, one of 26 counties in the current spotted lanternfly quarantine zone.

Insecticides and SLF

Homeowners who choose chemical control to deal with spotted lanternflies should research the pros and cons and use registered insecticides only.

IMAGE: Emelie Swackhamer

She encourages nonchemical control methods such as destroying egg masses, swatting the insects with fly swatters, trapping them and eliminating the tree of heaven. For homeowners who choose chemical control, she recommends they use a registered insecticide and research the pros and cons. It is good idea to use least toxic options first, including organic or natural-based insecticides such as neem oil or insecticidal soaps.

“People who want to kill spotted lanternflies effectively and safely with insecticides must follow directions carefully,” said Swackhamer. “Every situation is different; no one method will work for everyone. Remember, all insecticides present safety risks, so people must use caution with these products.”

Spotted lanternflies are luminescent. The origin of this fallacy most likely lies in the pest’s name, according to Julie Urban, associate research professor in the Department of Entomology.

“‘Lanternfly’ is a name that refers to the insect family ‘Fulgoridae,’ to which the spotted lanternfly and more than 500 other insect species belong,” she said. “These insects often possess unusual physical features, including an extension or enlargement of the head, as in the case of spotted lanternfly.”

At one time, scientists hypothesized these insects’ enlarged domes housed bioluminescent bacteria that could make them glow. This led to the insect family being named for “Fulgora,” the Roman goddess of lightning.

SLF family two

The spotted lanternfly, shown at left, is a member of an insect family that often possess unusual physical features, including an extension or enlargement of the head.

IMAGE: Julie Urban

While the spotted lanternfly possesses powers such as feasting on plants, depositing sticky honeydew and taking up residence anywhere, the ability to glow — or to fly well, for that matter — is not among them.

For the latest science-based information about the spotted lanternfly, visit the Penn State Extension website at https://extension.psu.edu/spotted-lanternfly or call 888-4BAD-FLY (888-422-3359). Extension also offers a monthly spotted lanternfly newsletter. To subscribe, visit https://extension.psu.edu/spotted-lanternfly.

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Last Updated January 20, 2021