I remember that first phone call in mid-September of 2014. A colleague I had not spoken with since graduate school left me a cryptic message, just asking me to call him back. But I immediately knew. The Lycorma had arrived.
If you live in New York City or Pittsburgh right now, you likely have a similar sense of dread today. Lycorma, shorthand for Lycorma delicatula, is the official name of the spotted lanternfly, a member of a group of sap-feeding insects known as “planthoppers.” They crawl up the sides of buildings; they feed at high densities (by the hundreds or even thousands) on single trees, where their sugary excrement, known as honeydew, rains downs on anything below and attracts stinging bees and wasps. Because honeydew is sugar-rich, a sooty mold often grows on it, which visibly blackens trees, understory plants, decking and lawn furniture. They flit around residential neighborhoods, where well-meaning amateur exterminators squash them, leaving piles of carcasses in their wake. They can appear, to the average person, to be a plague. But how bad is this infestation, really? The answer is a little complicated.
I have been involved with the spotted lanternfly threat for the last nine years. It may not seem that way to New Yorkers, but we’ve learned quite a bit in that time.
As an expert on planthoppers, I am familiar with spotted lanternflies. An invasive bug first detected in South Korea in 2004, its feeding was damaging grape vines, fruit trees, ornamental trees and timber, and its presence was an all-around nuisance in residential areas.
American regulators recognized the potential threat, too. Within two weeks of the initial detection in Pennsylvania, the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) and the Pennsylvania Department of Agriculture assembled a group of scientists to pool our expertise. As one member of that original group, I have been involved with the spotted lanternfly threat for the last nine years. It may not seem that way to New Yorkers, but we’ve learned quite a bit in that time.
Let’s start with the bad news: The spotted lanternfly has already spread widely, resulting in quarantines throughout most of Pennsylvania, as well as areas in New York, New Jersey, Delaware, Maryland, West Virginia, Ohio, Virginia, Massachusetts, Connecticut, Rhode Island, Indiana, Michigan and North Carolina. The spotted lanternfly is also a great hitchhiker that easily latches on to our vehicles and shipments. It has been detected in states like Vermont, New Hampshire, Iowa, Oregon, Washington and California, but is not known to have breeding populations.
It is a significant nuisance pest, feeding on over 70 different species of trees and plants found in North America. With such a broad diet, it tends to move across multiple habitats, feeding on plants across a range of landscapes: agricultural, urban, suburban, managed forests and parks. It can impact a wide range of agricultural and non-agricultural industries, including nurseries, Christmas tree growers, any business shipping goods in or through quarantined areas, and its impacts may change as and if its range continues to expand to new states and regions.
Grape growers so far appear to be the most affected. Based on field observations and research, the available evidence indicates spotted lanternflies feeding at high levels can cause damage and, over time, mortality to grapevines. Damage and impacts in associated industries such as agrotourism have been reported in vineyards in southeastern Pennsylvania and are likely expanding to infested areas in Virginia and New Jersey. Lanternfly populations are now moving closer to important grape-growing areas in New York’s Finger Lakes, Hudson Valley and Long Island regions, as well as vineyards along Lake Erie in Pennsylvania and Ohio.
Now for the good news: While the pests can damage grapevines and turn sidewalks into graveyards, they have not lived up to their apocalyptic hype. For ornamental, fruit and timber trees, lanternfly feeding is more of a stressor and will not outright cause tree mortality, although researchers and regulators remain vigilant to the potential threat they may cause as they expand into new areas. The lanternfly also does not bite or sting. It cannot hurt humans or pets. But it certainly can annoy them. That’s also a silver lining, however, in a way. The spotted lanternfly is highly conspicuous, easy to recognize, and its threat has been broadly communicated through public awareness campaigns in recent years. This increases the likelihood that if they show up in a new area — say in Chicago, St. Louis or Seattle — someone will see it and report it, allowing it to be quickly removed before a population can become established. Researchers are continuing to develop better management techniques to control lanternflies, particularly in and around vineyards (see StopSLF.org for some examples). USDA and state agencies are also continuing treatment efforts, prioritizing populations near airports, railways and other transportation hubs that could help facilitate small spotted hitchhikers. So, to answer the final burning question: Should you keep killing spotted lanternflies on sight? Unfortunately, the answer is “yes” because if you don’t kill it, you can carry it.
Julie Urban
Dr. Julie Urban is a research associate professor of entomology at Penn State University. She is an evolutionary biologist specializing in planthoppers and their co-evolution with microbial symbionts. 
