When the highly invasive spotted lanternfly was first discovered in the woods surrounding Kate Reed’s Winchester, Virginia, home, it occurred in such small numbers that finding it required a short trip and careful observation in a small area of trees. This year, the spotted lanternfly so heavily populated her community that neighbors complain of insects scaling buildings up to fifth-floor balconies and thick swarms of large adult lanternflies can be seen congregating on newly cut tree stumps of its preferred host species, tree of heaven.

“I had not seen them in downtown Winchester before this year," said Reed, a Virginia Cooperative Extension Master Gardener. “Now they’re all over.”

The spotted lanternfly has spread quickly in the two-and-a-half years since its detection. The pest, which poses a serious threat to Virginia farmers and can be an extreme nuisance for citizens, has expanded its range within the City of Winchester and Frederick County and to neighboring Clarke County. However, much of Virginia could eventually face similar infestations.

Loading player for https://video.vt.edu/media/Spotting+the+highly+invasive+spotted+lanternfly/1_1fu22f74...

Residents in Winchester and Frederick County now report large numbers of spotted lanternflies grouped on trees, buildings, and outdoor infrastructure. Businesses in the mandatory quarantine areas of Winchester and Frederick must inspect vehicles and materials being shipped elsewhere to ensure they are free of hitchhiking spotted lanternflies. In surrounding agricultural areas, farmers on the precipice of the pest’s expanding range wait to see how this new phloem-feeding insect will affect their crops.

In parts of Pennsylvania where the spotted lanternfly has been established since 2014, residents report that the insects affect their quality of life and ability to enjoy the outdoors during spring and summer months.

As spotted lanternflies feed on trees (causing such damage as oozing sap, wilting, and tree dieback), they excrete a sugary substance, called honeydew, which encourages the growth of black sooty mold. Spotted lanternflies will cover trees, create airborne swarms, and their sticky honeydew excretions can coat decks and outdoor play equipment.

When feeding on agricultural crops, such as fruit-bearing trees or grape vines, spotted lanternflies can substantially reduce yields, creating devastating impacts for farmers.

How - and when - will spotted lanternfly spread in Virginia?

“The scary thing about spotted lanternfly is that it's an extremely good hitchhiker and dead adults have been intercepted in cargo multiple times in Virginia,” said Eric Day, a Virginia Cooperative Extension entomologist who has been working to understand spotted lanternfly’s potential impact in Virginia. Fortunately, no live spotted lanternflies have been detected in cargo so far.

“It has the potential to establish throughout Virginia, but we don't really know when it will reach a particular location,” said Day. “Pennsylvania went from one county in 2014 to 25 in 2020. Virginia went from 1 square mile in 2018 to over 60 square miles in 2020. It's most likely to be spotty as it gets moved by humans.”  

According to Day, widespread infestation of another invasive species, tree of heaven or Ailanthus altissima, creates a second major concern.

“Spotted lanternfly’s preferred host is Ailanthus altissima, which grows along transportation corridors in Virginia and throughout the Eastern United States. This makes a convenient location for this insect to hop on and off of conveyances such as trucks and trains,” he said.

For example, a spotted lanternfly, or a well-camouflaged egg sack, hitching a ride on a truck departing from an infested area might find itself conveniently deposited on a road-side tree of heaven. In this way, a new population of spotted lanternflies could pop up nearly anywhere, making vigilance among members of the public key in the fight to monitor and control the insect’s spread.

What can be done to fight it?

Spotted lanternfly's black head, grey-brown spotted forewings, and bright crimson hindwings make them distinctive - even beautiful -and also easy for the general public to identify.  According to Day, this ease of identification has led to high accuracy in spotted lanternfly sighting reports in both Virginia and Pennsylvania, making it easier for state agencies to track the insect as it moves into new areas.

“We have been talking widely about this insect in Winchester and Frederick County now for three years,” Sutphin said. “Much of the community has gotten the message, is aware of the pest, and eager to report sightings. With each report, we are able to arm the resident with best management practices for their home or business along with a host of Extension resources.”

For Virginia Cooperative Extension’s spotted lanternfly resources, visit this website.

“Another thing going for us is a high amount of interest and survey participation by Master Gardeners. The data generated by Extension Master Gardeners has been extremely valuable,”  Day said.

“We have a team trained to help trap and monitor spotted lanternfly, then report that data back to state agencies,” said Dottie Farley, an Extension Master Gardener who, along with Reed, helps manage local efforts to provide public education and monitor the insect’s spread.

“We also have a working group that goes out to talk to local groups and do outreach, like putting signs in nurseries,” said Reed, who emphasizes the difficulty of getting citizens to act preemptively to remove host species or take other efforts to slow the insect’s spread.

“You might not care about them right now, but when you experience this density of insects in your own community, you will,” she said.

Frederick County has also become host to numerous scientific studies and trials, all of which aim to understand spotted lanternfly behavior, response to different pesticides, and potential management practices.

According to Sutphin, some local landowners are also working to remove the tree of heaven, or Ailanthus altissima, a highly important host plant for spotted lanternflies. Although the tree of heaven is not the only host plant for spotted lanternflies (others include apple trees and grape vines), tree of heaven’s wide range and tendency to grow along transportation corridors creates favorable conditions for new populations to become established.

In Virginia, collaborative teams from state agencies, universities, and local governments have mobilized to monitor the insect and work to understand potential methods of control.

Virginia Cooperative Extension works to monitor the insect’s spread, provide public education, assist property owners and farmers who experience insect-related damage, and assist researchers conducting spotted lanternfly-related fieldwork. Virginia Department of Agriculture and Consumer Services, as well as Virginia Department of Forestry, and local governments are also working to understand the insect and control its spread.

a group of spotted lanternfly adults grouped on a tree trunk as one lays eggs in the upper left, in the bottom right a pale brown egg mass is ready to overwinter
Spotted Lanternfly adults and a fresh egg mass on red maple (adult, second from top left is laying eggs). Egg masses will overwinter until the nymphs hatch in the early spring of 2021.

In Frederick County, the work continues

“The first egg masses for the 2020 season were observed on September 15 in Frederick County. This is the life stage that will over winter and become the 2021 population,” said Sutphin.

“Several days in September we exceeded 50 reports a day. We had reports of hundreds of adult spotted lanternflies clustered on individual buildings and structures,” he said, adding, “There is a short period each year when adults seem to aggregate to tall objects, oftentimes buildings, signs, or utility poles. I don’t think we fully understand this behavior but theorize it has to do with dispersal or mating behaviors. This phenomenon has been observed in Pennsylvania as well, even on high rise buildings in Philadelphia.”

“They haven’t reached my area yet, but they’re coming,” said Farley who lives in Shenandoah County. “I am concerned about how I will be able to control them in an environmentally friendly way, and how I will be able to help my neighbors--plus they’re just creepy!”

“Once they get here, it's just a question of where else they will spread to next,” she said.

Members of the public are asked to report any sighting through the Extension reporting portal, click here. You can learn more about the spotted lanternfly here.

Extension Master Gardeners bring the resources of Virginia’s land-grant universities – Virginia Tech and Virginia State University – to the people of the commonwealth. Contact your local Master Gardeners through your Extension office or click here to learn more about gardening in Virginia and the Virginia Extension Master Gardener program.

-       Written by Devon Johnson