The Spotted Lanternfly: Spread, Life Cycle, Treatment

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.

Spotted Lanternfly: The Basics

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.

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 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 Lanternflies Spread Through Hitchhiking

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, 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.

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.