Spotted Lanternfly Now Pervasive Across Prince William County

The Spotted Lanternfly is an invasive insect that can cause the decline, and sometimes death of more than 100 plant species in the area. The first sighting of the insect was confirmed in Prince William County in March of  2021. Since then, the pest has spread to all corners of the county.  

“We’ve found them all the way up north in Bull Run Mountain and all the way down south of Woodbridge. Efforts to mitigate the spread have, so far, been unsuccessful,” said Robin Firth, forest pest specialist with the county’s Mosquito and Forest Pest Management Branch. “They’re here, but they’re not something that’s going to hurt your family.”  

Spotted lanternfly, or SLF, is known to stress fruit crops with heavy feeding, but it is rare that the pest will kill trees or ornamental shrubs that are not stressed by other factors, such as drought or root damage. People who find the pest should not immediately cut down their trees.  

“It’s unlikely that they’re going to kill your plants, but if you’ve got, say a peach tree, that you’re used to getting peaches off of every year, if that tree is covered in SLF you’re going to see a reduction in the food crop from that peach tree,” Firth said.  

Instead, people who find the distinctive SLF should kill them if they can by spraying them with a 50/50 solution of dish soap and water. Isopropyl alcohol can also kill spotted lanternfly nymphs that are black upon hatching from the egg masses and later turn black with white spots before turning red with white spots.  

“All throughout the winter, you can look for egg masses that look like silver or grey mud smears and then scrape or squash them. During the early parts of the year, either trapping or squashing the nymphs is something people can do,” Firth said.  

Killing adult spotted lanternflies later in the year takes more work.  

“The other thing that people can do if they have Ailanthus altissima, known as Tree of Heaven trees, is buy systemic pesticides online that will be drawn up into the tree that they’re applying it to. So, the trees draw up the pesticide, then, when the spotted lanternfly drinks the sap from the trees, the insects are killed,” Firth said. “The active ingredient people should search for online is Imidacloprid 2F.” 

Treating native trees such as oaks, maples and walnuts will result in native species dying, as well as the lanternfly, so it should be avoided wherever possible. 

Assistant Director of Public Works for Construction and Operations, Luke Hisghman, said the spotted lanternfly is opportunistic in its feeding habits, so it is hard to control them by simply taking away their preferred food tree. 

“Even cutting down their primary food source – that tree of heaven – doesn’t really work because they’re not really that particular. They just move to a maple or whatever tree they can find,” Hisghman said.  

Those who see SLF in the county should report them to the Virginia Cooperative Extension, or VCE, on the website at https://bit.ly/reportSLFinPWC.  

Valerie Huelsman, VCE Environmental Educator, said people shouldn’t panic about the pest, though. The extension offers resources.  

“We’re still looking to encourage everyone to report them; and if they’re concerned about plants in their landscape, to get in touch with our horticulture help desk and we can give them research-based information on how to deal with the spotted lanternfly if they do find them and they’re concerned about the potential impact,” Huelsman said.  

For more information and to report spotted lanternfly sightings, visit pwcva.gov/slf or call the Mosquito and Forest Pest Management Branch at 703-792-6279 or the Virginia Cooperative Extension Prince William Unit at 703-792-6289.