The State We're In

As weather warms, watch for invasive spotted lanternflies

Mar 29, 2019

Spring is here and this state we’re in is greening up. Flowers are popping, bees are in action and buds are swelling.

But in the midst of this long awaited renewal, party-crashers are lurking. One uninvited guest is the spotted lanternfly, an invasive bug that feeds on a wide range of trees, plants and crops, and can cause significant damage.

Native to Asia, spotted lanternflies were accidentally introduced into Pennsylvania in 2014. Last year, they crossed the Delaware River into three New Jersey counties – Mercer, Hunterdon and Warren. The challenge is to stop their spread and eradicate them.

Below, Rosa Yoo, regional forester with the New Jersey Forest Service, explains why spotted lanternflies are a threat, how to recognize their life stages, and what you can do if you see one.

What is a spotted lanternfly?

It’s a non-native insect in the plant hopper group of insects. In their first three instars (phases between molting their skin), nymphs are black with white spots. In their fourth instar, they’re red with white spots. Adults have a black head, grayish-brown forewings with black spots, and red hind wings with black spots.

How do spotted lanternflies damage trees and plants?

Unlike some insects, they don’t eat leaves and fruit. Their mouth parts are like a long straw, and they pierce the plant tissue and suck out the sap or fluid. Nymphs have softer mouth parts, so they feed on tender plants and new growth. Adults can pierce the bark of trees.

Which plants do they like most?

Spotted lanternflies have a preference for Ailanthus altissima, the Tree of Heaven, and grapes – both orchard and wild grapes. In Pennsylvania, they’re fond of feeding on apple and peach trees, basil plants, vegetables and hops. They like many trees, including black walnuts, maples, willows and cherries. The list seems to be growing, not shrinking. There are over 70 trees and plants that lanternflies feed on.

How can someone recognize lanternfly damage to a tree or plant?

When lanternflies are piercing a tree, the wound will be weeping and wet-looking. Lanternflies also excrete a sweet substance called honeydew. Mold grows on the honeydew, and the honeydew can attract other insects like ants or bees.

Do trees and plants die quickly if infested with spotted lanternflies?

Studies are going on now to determine the threshold at which plants cannot survive. What the studies are finding is that it takes heavy feeding by spotted lanternflies over consecutive years to affect the health of a plant. But at some point, the plant isn’t able to catch up with the loss of fluids and becomes too weakened to survive.

How do spotted lanternflies spread from place to place?

Adults are able to fly, but not for long distances … they generally jump or hop. But they’re good hitchhikers. During the times when adults are active, they’ll hitch rides inside your vehicle. And they’ll lay their eggs on just about anything, including cars, outdoor furniture and wood. That’s why it’s really important for people to look for egg masses if they’re in a county with spotted lanternflies.

What’s being done to keep spotted lanternflies from spreading beyond Mercer, Hunterdon and Warren counties?

Those three counties are under quarantine, as are the counties in Pennsylvania where spotted lanternflies are found. The quarantine puts limits on the movement of articles from within the quarantine area to places outside quarantine.

Is spring the time to be on the lookout for spotted lanternfly egg masses?

Yes. Adult lanternflies spent last fall laying eggs, and the eggs will hatch in May and June.

How can you identify a spotted lanternfly egg mass?

The egg masses are difficult to see because they look like a splotch of mud. They can be found on any flat surface, including underneath picnic benches, under and on the bark of trees, on parked vehicles and equipment, and in other protected places.

What should you do if you spot an egg mass this spring – or a nymph or adult this summer?

If you see an egg mass, nymph or adult, take a photo and email it to the New Jersey Department of Agriculture at With an egg mass, you can remove it yourself by scraping it into a plastic zipper bag with alcohol or hand sanitizer, sealing it and throwing it out. You can also report sightings by calling the Department of Agriculture hotline at 1-833-223-2840 (BADBUG0).

For more information on spotted lanternflies, go to To learn about other invasive animals and plants, visit the New Jersey Invasive Species Strike Team website at

And to learn about preserving New Jersey’s land and natural resources, visit the New Jersey Conservation Foundation website or contact me at

About the Authors

Alison Mitchell

Co-Executive Director

John S. Watson, Jr.

Co-Executive Director

Tom Gilbert

Co-Executive Director, 2022-2023

Michele S. Byers

Executive Director, 1999-2021

View their full bios here.


Get The Latest News
From The Garden State

In the



Translate »