Spotted lanternflies (SLFs) are native to southeast Asia, but they have made their way to the United States in recent years. The first U.S. sighting happened in Berks County, Pennsylvania, in 2014, and since then, they’ve popped up in every state Pennsylvania borders (and a few it doesn’t).
In just 7 short years, SLFs have spread to New York, Massachusetts, Connecticut, Rhode Island, New Jersey, Delaware, Maryland, Virginia, West Virginia, eastern Ohio, and southeastern Indiana—and they did it without flying. As the Penn State Extension program explains, SLFs are exceptionally effective hitchhikers, which is how they get around:
Adult SLF[s] can hold onto vehicles moving at 65 MPH, and egg masses that look like a splash of mud can be hidden on any surface, easily blending in and moving with you anywhere in the Commonwealth and beyond.
While these bugs aren’t dangerous to people or pets, they’re an invasive species. They use their piercing-sucking mouthparts (I’m so sorry you had to read that) to feed on tree sap, particularly that of tree of heaven (Ailanthus altissima). They then excrete a sugary substance called “honeydew” that both attracts flies and wasps and encourages the growth of black sooty mold. This type of mold doesn’t hurt people, but it causes further harm to plants and is, frankly, super gross; in severe cases, SLFs have been known to blanket entire trees, vehicles, decks, and play structures with their nasty, sticky, sugar-poop.
Basically, these bugs kill trees by draining them of sap, then make things worse by pooping out wasp bait that doubles as a growth medium for mold. This has concerning implications for crops grown on trees: Although tree of heaven is their usual food source, Cornell University’s “Have You Spotted [a] Lanternfly?” guide reports that SLFs will eat a wide variety of crop trees and vines, including grapes, black walnut, willow, hops, apples, stone fruit, silver maple, and others.
Your state may not have a spotted lanternfly problem right now, but that may not be the case forever. It’s important to understand what these insects look like and how to kill them.
Learn what they look like at all stages of life
Spotted lanternflies have a distinct life cycle, and you should know what they look like at every point in their development. Cornell University’s Cooperative Extension and the Penn State Extension program are great resources for all things spotted lanternfly. Both programs have produced tons of visual aids to help with identification, like this YouTube video from the Penn State Extension channel:
Here’s a quick rundown of what to look for:
- Egg masses: Freshly-laid eggs look kind of like smeared mud and can be found on trees, cars, buildings—pretty much any surface
- Old egg masses: The putty-like covering has worn off, exposing individual seed-like eggs
- Early nymph: Small, black oval body with white spots; 1/8 to 3/4 inch long
- Late nymph: Small, red oval body with white spots and black markings; 3/4 inch long
- Adult, wings closed: Larger, more oblong body with closed, translucent white wings and distinctive black spots; 1 inch long; 1/2 inch wide
- Adult, wings open: Larger, more oblong body with open, translucent white and red wings with distinctive black spots; 1 inch long; 1 inch wide
It’s also helpful to know which stages happen when. Here’s a very basic timetable from Cornell’s “Have You Spotted Lanternfly?” resource:
- September-November: SLFs begin laying eggs for the season
- October-June: Eggs mature
- May-June: Eggs hatch; larvae develop into early nymphs
- June-July: Early nymphs
- July-September: Late nymphs
- July-December: Adults
Right now, you’ll probably see mostly adults and late-blooming nymphs—but that means egg-laying season is just around the corner.
Kill them. Kill them all.
There are no natural predators in the U.S. to help control the population, which means it’s up to us to kill them. For individual, hatched SLFs of any age, this is pretty straightforward: Squish ‘em, step on ‘em, whack ‘em with a rolled-up newspaper, do whatever you have to do to kill them dead. (The last summer I lived there, it was obvious that the beautiful people of Philadelphia were taking this assignment seriously: The Schuykill River Trail was absolutely plastered with SLF corpses from June to December.) As for the eggs, Penn State recommends using a paint scraper or similar thin, stiff, flat tool to scrape masses off surfaces and into rubbing alcohol.
If you notice a full-on infestation—like a tree on your property that’s covered with the things—the Penn State Extension recommends buying or DIY-ing a circle weevil trap. These traps use plastic insect screening and the neck of an old plastic jar or bottle to create a kind of death tunnel for SLFs. You can easily attach them to trees without damaging the tree itself or accidentally harming other forms of wildlife, which is always a risk with sticky traps. If you feel out of your depth at any point, use this guide from Penn State to help you choose a qualified pest management company.
Whether you’re going to DIY or hire professionals, beware of home remedies you may have seen online. According to the Penn State Extension, untested remedies like vinegar, Borax, soap, garlic, and chili peppers probably won’t work all that well and could end up damaging your garden or property even further.
Document and report sightings
If you see any number of SLFs, in any life stage, you should contact your state’s department of agriculture. Be sure to take lots of pictures—preferably with a coin, ruler, or other standard for scale—and submit them. Here’s a list of reporting resources for states with confirmed cases (each state’s name links to a more general information page):
For states without confirmed cases or infestations, your best bet is to Google your state’s name with “spotted lanternfly report” and see what pops up. There may be a system in place already. If not, honestly, it’s only a matter of time until there is one. Until then, stay vigilant and kill ‘em all.