UNIVERSITY PARK, Pa. — The first step in deciding how to manage spotted lanternflies on residential properties and public spaces begins with a risk assessment, according to a Penn State Extension horticulture educator.
“Spotted lanternfly is a complex pest problem, and unfortunately, there is no ‘one size fits all’ solution,” Emelie Swackhamer said. “While spotted lanternflies can weaken landscape trees, they usually do not kill them, so that’s an important factor to consider when deciding on a control method.”
The spotted lanternfly, an invasive insect from Asia, was discovered in North America in Berks County in 2014. The pest since has spread to at least 34 Pennsylvania counties. It also has become established in New Jersey, New York, Connecticut, Delaware, Maryland, Ohio, Virginia and West Virginia.
The planthopper feeds on important agricultural commodities — including grape vines, fruit trees, nursery plants and hardwood timber — and on plants in natural habitats, parks and backyards.
Many residents’ concerns center on the pest’s ability to harm ornamental trees on their properties, leading them to seek information on the why and the how of spotted lanternfly feeding.
Kelli Hoover, professor of entomology in Penn State’s College of Agricultural Sciences, explained that the pest uses its piercing/sucking mouthparts to punch into the tree and feed on the sap, which contains sugars and some nutrients.
While the spotted lanternfly’s preferred host in its early life stages is Ailanthus altissima, also known as tree of heaven, it will feed on plants including multiflora rose, cultivated roses, Virginia creeper, and the veins of leaves on trees such as maples, cherry, black walnut, willow and birch.
When spotted lanternflies mature, their food preferences narrow, noted Hoover. Adults prefer tree of heaven or cultivated grape, but they will switch over to red and silver maples and occasionally to other trees such as sycamore, willow and river birch in the fall. The pest rarely feeds on oaks, and it does not appear to like conifers.
“We have no idea what makes a tree of the same species as its neighbor more attractive,” said Hoover, whose research focuses on finding an answer. “Colleagues in our department have reported that it may have to do with nitrogen content, but more information is needed. It’s a bit like looking for a needle in a haystack to figure out, but we continue to search for answers.”
Hoover pointed out that while spotted lanternflies can and do kill tree of heaven and cultivated grapes, they rarely kill other tree species. However, when large numbers of spotted lanternflies feed on one tree, it must affect that tree, and her team is working to measure those effects. A stressed tree may be more susceptible to other stressors such as disease, insect pests or drought.
She added that saplings are more likely to experience significant stress from spotted lanternfly feeding than mature, established trees.
As homeowners mull over what to do about spotted lanternflies, Swackhamer and extension colleague Amy Korman suggest that they weigh the advantages and disadvantages of various methods. That starts with assessing spotted lanternfly population size and life stage, time and money involved in treatments, the species of trees and plants on which the pest is feeding, and whether the property is close to a vineyard or central transportation corridor that would enable the pest to hitch a ride to another area.
After thinking realistically about the risk, the next step is to decide on a course of action. Korman recommends integrated pest management, which focuses on effective management options in an ecologically responsible way. “We encourage using nontoxic, effective options first, including mechanical methods such as smashing or trapping,” Korman said.
One option is a circle trap, which is a funnel-style device that wraps around a tree trunk. Nymphs and adults are guided into a container — usually a plastic jug or bag — at the top of the funnel as they move upward to feed on the tree. Though circle traps can catch nontarget species, the potential is significantly lower than with the use of sticky bands on trees.
While circle traps can capture a significant number of spotted lanternflies on individual trees, they do not prevent lanternflies from moving around in a landscape and returning, Korman emphasized.
Sometimes the use of an insecticide is a viable option, Swackhamer said. However, because there are safety, environmental and sometimes regulatory concerns that accompany the use of insecticides, residents must follow label instructions, use registered insecticides only and select the least toxic products.
“The search for ‘softer’ pesticides is easy,” Swackhamer said. “Look for products that include a logo from the Organics Material Review Institute — OMRI — or a ‘caution’ signal word on the label. If you have any qualms about using these products, it’s best to contact a qualified pest management or lawn care company.”
Home remedies such as cleaning solutions and other household products can be unsafe for humans, pets, wildlife and plants. In some cases, the application of home remedies may be illegal.
The bottom line, the educators say, is to avoid overreacting to spotted lanternflies and perhaps overtreating the problem. “To date, we have not observed spotted lanternflies killing otherwise healthy ornamental trees in landscapes,” Korman said.
More information can be found online at https://extension.psu.edu/
–Amy Duke, Penn State University