The insects, thankfully, do not bite humans but cause major damage to plants, including oozing sap, wilting, leaf curling and tree dieback. The insects specifically target and feed on nutrient-rich phloem sap from trees, which causes physical damage.
As they feed, they also excrete some of the sap as a sugary waste product called honeydew. The honeydew encourages the growth of a fungal disease called sooty mold, which can indirectly damage the plant. The sooty mold coats plant leaves and prevents sunlight from reaching the leaves’ surface. Without proper sunlight, plant growth is stunted, and the affected leaves can die prematurely.
“The honeydew fouls foliage and fruit. The fruit becomes unmarketable, thus presenting a huge economic problem for growers of apples, cherries, peaches and grapes,” said Michael Raupp, professor of entomology at the University of Maryland. Grapevines and tree fruits (apples, peaches, etc.) are most at risk.
The spotted lantern fly will also move into wooded and residential areas to feed on other types of trees, such as maples or willows. The insects don’t kill the residential trees, but they produce a tremendous amount of honeydew that coats the ground and lawn furniture, attracts yellow jackets and leads to the growth of sooty mold.
To date, more than 1.5 million of the insects have been killed by volunteers in Berks and surrounding counties, Raupp said.
The map below shows areas of infestation and sightings.
Lantern fly quarantines, outlined on red in the map, prohibit their transport. The quarantines in place in southeast Pennsylvania and portions of Delaware, Maryland, Virginia and New Jersey are meant “to stop its spread to new areas and to slow its spread,” according to Raupp.
Despite having wings, the adults don’t fly far. The bugs are often spread by vehicles. Residents in quarantined counties are urged to inspect vehicles and goods for transport to ensure that the insects and their egg masses are not hitching a ride.
“If females lay eggs on a substrate that eventually moves (e.g., automobiles or goods), then they quickly spread that way,” Josephine Antwi, a professor of biology at the University of Mary Washington in Fredericksburg, wrote in an email.
Adults lay eggs September through December, while egg masses have been spotted from September to June. Egg masses hold about 30 to 50 eggs and are approximately one inch in size. Females can lay up to two egg masses, typically on flat surfaces including tree bark, rocks, lawn furniture, RVs or anything left outdoors. Although the adults don’t survive through the winter, the eggs can.
“When females lay eggs, they cover them with a putty-like material that hardens with time. This material serves to protect the eggs and secure them to any surface they’re laid on,” Antwi wrote.
So far, Wayne Mills, vineyard operations manager for the Winery at Bull Run, has not spotted the insect. But he is worried. Mills manages vineyards in Fairfax, Fauquier, Loudoun and Rappahannock counties.
Though the spotted lantern fly doesn’t kill most trees, it can kill grapevines. Vineyards in Pennsylvania have been hit particularly hard. And if the vines survive, the grapes are tainted with the insect’s honeydew, resulting in sooty mold, and can’t be used for winemaking.
Mills emphasized that the spotted lantern fly’s favorite tree is the tree of heaven, which is an invasive tree native to China. The tree of heaven lines many of our highways because it thrives in poor soil conditions, which exist where road construction disturbed topsoil. Thus, the bug may follow our roads and eventually spread across the Washington region. Mills is hoping an insecticide is quickly approved for use against spotted lantern flies in his vineyards.
Introducing a new predator for the spotted lantern fly is another hope for reducing the pest population. A tiny wasp found in China, Dryinus browni, lays its eggs inside baby spotted lantern fly nymphs, which later hatch into larvae and feed on the nymphs, killing them. But introducing another invasive species is a risk, and research is being done at the U.S. Department of Agriculture’s Beneficial Insects Introduction Research Unit before releasing the wasp in the United States.
In addition, research is being conducted at Cornell University to find a fungus to kill the spotted lantern fly, similar to how a fungus was used to control the gypsy moth population.
Meanwhile, if you encounter the spotted lantern fly, you’re encouraged to squish it. Recently, a “Squish Squad” of students in Pennsylvania mobilized to stomp out the pest.
But for now, in most of the Washington area, we await the dreaded bug’s arrival. Unfortunately, it should happen soon.