spotted lanternflies in southeastern PA

What You Need to Know About The Spotted Lanternfly

When mother nature’s checks and balances aren’t in place, invasive species can run rampant. That’s what we’ve experienced over the past several years with the spotted lanternfly (SLF) – an invasive planthopper with few natural predators that’s taken a liking to many of the trees here in Southeastern Pennsylvania. Every year, we continue to see the sprawl of the spotted lanternfly expand.

In this article, we will give you a full overview of SLF. We’ll explain the insect’s life cycle, how it attacks your plants, and what you should do when you identify SLF on your property.

Key Takeaways:

  • Spotted lanternflies are an invasive species from China and Vietnam that feed on trees and excrete honeydew.
  • Researchers from the Penn State University Extension service suggest SLF does not kill most mature trees, though their feeding stresses trees and can cause dieback and defoliation.
  • Spotted lanternflies have one generation per year that goes through five distinct phases: egg mass, early nymph, late nymph, closed-wing adults, and open-wing adults.
  • Lancaster County and much of the surrounding area is under quarantine for SLF; always check your vehicle before leaving the area for SLF attempting to hitchhike.
  • We recommend targeted treatments in the summer to avoid harming beneficial bugs.

What Is a Spotted Lanternfly?

Spotted lanternflies (Lycorma delicatula) are an invasive species native to China and Vietnam that has spread throughout the United States since its introduction in 2012. They feed on plants during the summer, stressing and defoliating them.

SLF is not just a nuisance to plants but to humans in Pennsylvania. They excrete honeydew, a sweet waste product that attracts other insects like wasps. The Pennsylvania Department of Agriculture estimates that SLF’s attacks on plants could cost the state $324 million annually and more than 2,800 jobs.

PRO TIP: Penn State University Extension is one of the leading institutions researching and developing our understanding of SLF. If you need more information, they provide numerous resources on their website about dealing with SLF in Pennsylvania.

Several adult spotted lanternflies on a tree with sooty mold developing at the base of the tree in Lancaster, PA.
The honeydew excreted by spotted lanternflies can cause sooty mold on a tree and its leaves.

How Spotted Lanternflies Harm Your Trees

Since its introduction to Pennsylvania, arborists have been studying SLF’s effect on our native trees. Arborists originally believed SLF would pose a danger to native trees and kill them within a few seasons.

Research spearheaded by the Penn State University Extension in 2023 suggests trees may not be in life-threatening danger from SLF.

Researchers conducted a test over several seasons where native trees were exposed to consistent SLF activity. Over the first two years, the trees showed decreased diameter growth due to a reduction of key nutrients. However, after the researchers reduced the SLF population, they found the native trees had begun to recover.

Tree of heaven, an invasive tree and favorite target of SLF, was the only species in the test that did not recover from SLF activity.

Although your trees may not be in life-threatening danger from SLF, any insect activity will stress your tree, leaving it struggling and more susceptible to other insects, diseases, and drought. Aside from stress, consistent SLF feeding can cause several problems for trees, including:

  • Wilting leaves
  • Defoliation
  • Dieback

In addition to the damage from feeding, the honeydew SLF excrete can act as a growth medium for the sooty mold fungi. Sooty mold not only makes your trees look ugly, but it can also restrict the photosynthesis of leaves, which is vital to the tree’s health.

Some of the common trees SLF is attracted to include:

  • Birch
  • Walnut
  • Cherry
  • Pine
  • Oak
  • Maple
  • Beech
  • Dogwood
  • Several varieties of fruit trees
  • Ash
The five stages of the spotted lanternfly.
In one year, spotted lanternfly go through five stages. They are (from left), egg mass, early nymph, late nymph, closed-wing adult, and open-wing adult.

The Spotted Lanternfly Life Cycle Consists of 5 Phases

Spotted lanternflies go through dramatic transitions in body size and color from the early spring through the fall. Their life cycle is broken down into five phases.

  • Phase One – Egg Mass: Egg masses start to show on trees in April and usually start to hatch between the end of April and as late as June, depending on the temperature. Each egg mass is the home of up to as many as 40 eggs.
  • Phase Two – Early Nymph: Once the eggs hatch, the spotted lanternflies go through an early nymph stage and a late nymph stage. Early nymphs are black with white dots. In our region, we’ll start seeing early nymphs as early as late April through July.
  • Phase Three – Late Nymph: By the time they’ve reached the late nymph stage, spotted lanternflies have red bodies with white spots and black legs. In our region, they’ll reach this stage around July and stay this way until September.
  • Phase Four – Closed-Wings Adult: In this stage, SLF grows spotted wings that stay closed. Depending on the temperature, adults can emerge as early as July, but are more common in early fall.
  • Phase Five – Wings-Open Adult: Finally, the spotted lanternfly reaches its second adult stage in the fall. Its wings open, and it begins to fly. Now, it’s out to find a tree and create a nest to lay its eggs before the cold weather hits.

The eggs overwinter until the cycle repeats. SLF has only one generation per year.

Spotted lanternfly nymphs on a tree in Lititz, PA.

How Do Spotted Lanternflies Spread?

One of the biggest reasons that spotted lanternflies are so hard to control is that they love to hitchhike. They’ll find their way onto cars, campers, and any other vehicle they can. Then, when you travel outside the area, the lanternflies hop a ride to new regions of the country. This is largely how they’ve migrated down the east coast, moving further south and west every season.

For this reason, a good portion of Pennsylvania, including Lancaster and the surrounding counties, are spotted lanternfly quarantine zones. If you plan to drive outside the county, check your car for spotted lanternflies before you go. Look under the hood, on each side of the vehicle, and around the tires.

PRO TIP: The PA Department of Agriculture asks residents to report sightings of SLF to help understand its spread and establish quarantine zones. You can report SLF sightings online or by calling the department at 1-888-422-3359.

What Should You Do if You See Spotted Lanternflies on Your Property This Summer?

If you begin searching for egg masses in April, you can strike early and remove them from your trees. The best way to do this is to scrape the egg mass into a paper towel soaked in rubbing alcohol and dispose of it.

Once the eggs hatch and the young black-and-white nymphs appear, try to resist the temptation to start treating your trees immediately.

Our arborists recommend waiting to treat the lanternflies until later in the summer during their adult phases. We use targeted treatments in the summer rather than broad-spectrum insecticide foliar treatments in the spring for two reasons:

Reason #1: Early Spring Broad Spectrum Treatments Only Harm the Good Bugs

If you do broad-spectrum insecticide foliar treatments across your yard to prevent spotted lanternflies from setting up camp in your trees, you’ll do more harm than good. That’s because spotted lanternflies fly from tree to tree, moving around the region they’re in. If you spray your trees in the spring, you’ll harm the good insects only to have new, healthy spotted lanternflies fly in days or weeks later.

Reason #2: Summer Treatments Are Targeted, Going After the Adults as They Move Back into the Trees

By waiting to treat a spotted lanternfly infestation until at least August, our plant care specialists can take a much more targeted approach. A systemic treatment targets female adults who feed on the host tree before laying their eggs. You’re more likely to kill the lanternflies this way and less likely to damage your other trees, shrubs, and the good insects around your yard.

Spotted Lanternfly FAQs

When did the spotted lanternfly get here?

First discovered in 2014 in Berks County,  the spotted lanternfly has been moving in all directions since then, blanketing Lancaster County and continuing to spread.

What is the government doing to stop spotted lanternfly infestations?

In May of 2018, the Pennsylvania Department of Agriculture announced a spotted lanternfly quarantine, covering 26 counties, according to the PA Department of Agriculture’s Spotted Lanternfly Alert. In 2021, eight more counties were added to the quarantine, bringing the total number of Pennsylvania counties under spotted lanternfly quarantine to 34.

Businesses and organizations that move vehicles in and out of the quarantine zone must get a spotted lanternfly permit. Residents are asked to use this spotted lanternfly checklist before moving outdoor items, such as travel trailers, outside of the 26-county quarantine zone.

My trees have been treated – why are there still lanternflies on there?

The treatment doesn’t put a giant protective bubble over your property. The insects can still fly in from other properties. What the treatment does is protect your tree. When they try to feed on it, they die.

What can I use to kill spotted lanternflies?

You should avoid home remedies to control spotted lanternflies, says Penn State Extension. The Internet is full of them, including dish soap, vinegar, salt, boric acid, vegetable oil, and more. They can harm humans, pets, and plants.

The best approach is to have a Certified Arborist apply a systemic pesticide that will remain in the tree and kill all insects that feed on it. This not only protects the trees but is better than indiscriminately spraying the landscape. We believe it’s impractical and environmentally unsound to spray the insects directly.

Do spotted lanternfly eggs die off in winter?

No. The adults die, but the eggs survive.

Will spotted lanternflies infest all my trees?

No. They are attracted to some trees more than others, even trees of the same species, for no discernible reason.

How long does your treatment last?

One growing season. So yearly treatment is needed.

Will they be back next year?

Yes.

What is the black goo all over the trees?

The bugs use a piercing-sucking mouthpart to tap into the tree’s fluids and excrete honeydew, or sugary water. This sugary substance encourages the growth of black sooty mold, which is harmless to people but attracts other insects. At a minimum, it is bothersome and unsightly, and at most, it can be damaging to the tree or the plants underneath it.

How many treatments do I need to get rid of spotted lanternflies?

This question contains a faulty assumption. As arborists, our mission is to protect your trees, not to eradicate spotted lanternflies from your property. In fact, there is no way to prevent the spotted lanternfly from moving onto your property, and we believe that should not be your focus.

By annually treating your most valued trees, we can protect them from the damage spotted lanternflies cause (and in the process, kill all of the insects that attempt to feed on the tree).

I can see what looks like egg masses. What should I do?

Scrape the mass using a piece of plastic or wood into a container of rubbing alcohol or sanitizer. If you feel like getting physical, you can squash the eggs to destroy them instead. To learn more, watch this video from Penn State Extension about destroying spotted lanternfly egg masses. Then, we encourage you to use the Pennsylvania Department of Agriculture’s spotted lanternfly reporting tool.

Do spotted lanternflies bite or sting?

No.

Will your spotted lanternfly application hurt my pets and kids?

No. Just keep them away from the tree for a couple of hours until it dries.

Why not just spray all trees?

Indiscriminate spraying is environmentally irresponsible. Insecticides will kill not just spotted lanternflies but beneficial insects in the ecosystem, such as butterflies.

Will the spotted lanternfly kill my tree?

There is no documented case of the spotted lanternfly killing a mature tree. It is possible, though, that heavily infested saplings could die. However, heavy feeding by spotted lanternflies does weaken the tree and can make it susceptible to other maladies, such as secondary insects and diseases. When the tree’s defenses are down, secondary pests can come along and kill the tree.  So, while it’s not a tree-killer like the emerald ash borer is to ash trees, it is bad for the tree and should be controlled.

Arborist Enterprises Can Treat Your Property to Keep Spotted Lanternflies from Taking Over

With little hope of eradication in the near future, the only thing to do with SLF is to contain it and protect the environment of Lancaster County as best we can. We all need to be aware of SLF’s presence and life cycle so we can chip away at the population and protect our trees.

If your property is home to the trees spotted lanternflies love most, treating your property in late summer can help. The team at Arborist Enterprises can come out and put together a spotted lanternfly treatment plan to help suppress spotted lanternflies on your property and support the health of the rest of your trees and plants.

Contact us today by requesting a proposal online or calling us at 717-393-7602.