If you’re reading this, chances are you’ve already seen spotted lanternflies (SLFs), or at the very least, you’ve heard about their presence in Maryland and Pennsylvania.
Native to parts of Asia, it was first identified in the U.S. back in 2014, when entomologists found the insect in Berks County. Since then, these insects have spread rapidly throughout the Mid-Atlantic and become an increasingly common sight on trees, patios, outdoor furniture, and vehicles.
While SLFs aren’t dangerous to people or pets, they can be a significant nuisance and cause damage to a wide variety of trees and plants. We’ll explain everything you need to know about these pests, so you can protect your landscape and limit their impact.
What Is the Spotted Lanternfly?
Despite its common name, the SLF isn’t a fly at all — it’s something scientists call a “true bug” (order Hemiptera). More specifically, it is classified as a planthopper.
Equipped with piercing-sucking mouthparts, the insect feeds on the sap of various plants and trees, known as “hosts”. Part of what makes this pest so noteworthy is that, unlike some other pests who only damage a small number of species, the SLF feeds on more than 100 different host species.
In an ironic twist of fate, the SLF’s preferred host is the problematic invasive, the tree of heaven (Ailanthus altissima). However, it will feed on many native species in Maryland and Pennsylvania, including black walnuts (Juglans nigra), maples (Acer spp.), willows (Salix spp.), and others.
Is Spotted Lanternfly a Problem for Maryland and Pennsylvania Trees?
Yes, the SLF can damage trees in our region, but they don’t always do so in the way many homeowners expect.
Unlike emerald ash borer, hemlock woolly adelgid, and several other invasive insects, spotted lanternflies do not typically kill otherwise healthy trees on their own. But their feeding behavior can place significant stress on trees when large populations are present.
Over time, heavy infestations can weaken trees and make them more susceptible to other environmental stressors, including drought, disease, and poor growing conditions. Meanwhile, several plant species, particularly grapevines, are more vulnerable and often suffer substantial damage from SLFs.
Aside from the stress they cause trees, SLFs also cause problems for homeowners and property managers. Spotted lanternflies often congregate in large groups, producing sticky honeydew — a sugary waste product that coats leaves, decks, outdoor furniture, and vehicles.
This honeydew frequently promotes the growth of black, sooty mold and can create a significant nuisance throughout the growing season.
Signs of a Spotted Lanternfly Infestation
Because SLFs are relatively large and often gather in noticeable numbers, infestations are usually easier to spot than those caused by many other tree pests. However, by learning to recognize the early signs of an infestation, you can take action before populations become overwhelming.
Common signs of a SLF infestation include:
- Large Numbers of SLFs: Adult SLFs are approximately one inch long with gray forewings covered in black spots and striking red-and-black hindwings that are visible when they fly. Immature nymphs are black with white spots when young and develop bright red coloration as they mature.
- Sticky Honeydew Deposits: SLFs excrete large amounts of sugary honeydew while feeding. You may notice sticky surfaces beneath infested trees or on patios, outdoor furniture, vehicles, and sidewalks.
- Black, Sooty Mold Growth: Honeydew provides an ideal growing medium for sooty mold fungi. This causes a black discoloration on leaves, bark, or nearby surfaces that is often a telltale sign of prolonged feeding activity.
- Oozing Wounds on Bark: Heavy spotted lanternfly feeding can occasionally cause small wounds on trunks and branches to ooze or weep sap. Oozing wounds are most commonly observed on heavily infested host trees during periods of intense feeding activity.
- Egg Masses on Outdoor Surfaces: During the fall and winter, spotted lanternflies lay egg masses that resemble smears of wet or dried mud. These may be found on trees, firewood, lawn furniture, vehicles, stone, or virtually any smooth outdoor surface.
- Other Insect Activity: The sugary honeydew produced by SLFs attracts a variety of other insects, including ants, yellow jackets, bees, flies, and other opportunistic feeders. Increased insect activity is often one of the first clues that a large SLF population is present nearby.
Treatment Options for Spotted Lanternfly
The most effective treatment strategy for SLF depends on the size of the infestation, the species being affected, and the goals for your landscape. In many cases, professional management focuses on reducing populations and minimizing stress on valuable trees and plants rather than attempting complete eradication.
Some of the most common treatment options include:
- Systemic Insecticide Treatments: Soil-applied or trunk-injected systemic insecticides can help protect trees by killing SLFs as they feed. These treatments are often used on high-value landscape trees that experience recurring infestations.
- Targeted Insecticide Applications: In some situations, professional bark sprays or contact insecticide treatments may be used to reduce SLF populations. Timing is critical to maximize effectiveness while minimizing impacts on beneficial insects.
- Tree-of-Heaven Management: Because tree-of-heaven is the SLF’s preferred host plant, properly managing or removing these invasive trees can help reduce local populations. Eliminating nearby tree-of-heaven may make your property less attractive to SLFs.
- Egg Mass Removal: SLF egg masses can be scraped from trees and outdoor surfaces during the fall and winter before they hatch in the spring. While this method is unlikely to eliminate an infestation on its own, it can help reduce future populations.
Note that the most successful SLF management programs often combine multiple strategies, including monitoring, targeted treatments, host plant management, and cultural practices designed to minimize impacts on desirable landscape plants.
Frequently Asked Questions About the Spotted Lanternfly
SLFs have become an unfortunate fact of life throughout much of Maryland and Pennsylvania. Here are answers to some of the questions homeowners ask us most often.
Are spotted lanternflies harmful to humans or pets?
No. SLFs do not bite, sting, or transmit diseases to humans or pets. They are primarily a nuisance pest that feeds on plants and trees.
Can spotted lanternflies kill trees?
SLFs do not typically kill healthy landscape trees on their own, though large infestations can place significant stress on trees and other plants. When combined with drought, disease, or other environmental stressors, this can lead to a tree’s death in some cases.
What time of year are spotted lanternflies most active?
SLFs are generally active from spring through late fall. Nymphs emerge in the spring and early summer, while adults are most noticeable from midsummer through fall. Egg masses overwinter and hatch the following year.
Should I kill spotted lanternflies if I see them?
Yes. If you encounter SLFs on your property, it’s generally recommended to destroy them whenever practical. Crushing individual insects or removing egg masses can help reduce local populations, although professional treatment may be necessary for larger infestations.
How do I identify spotted lanternfly egg masses?
Egg masses typically resemble smears of wet or dried mud and may contain 30 to 50 eggs. They can be found on tree bark as well as outdoor furniture, vehicles, firewood, fences, and other smooth surfaces during the fall and winter months.
Do spotted lanternflies only feed on trees?
No. SLFs feed on a wide variety of plants, including grapevines, fruit trees, ornamental plants, and shrubs. Although they are frequently found on trees, they are capable of utilizing many different host species throughout their life cycle.
When should I call an arborist about spotted lanternflies?
If you’re noticing large numbers of SLFs, sticky honeydew deposits throughout your property, or recurring infestations on valuable landscape trees, an arborist can help determine whether treatment is appropriate and recommend the most effective management options for your situation.
Protect Your Trees with Baker Tree Services
SLFs are certainly a nuisance, but they can also place significant stress on valuable shade trees and ornamental plants. If you’re seeing large numbers of these invasive insects on your property, it’s time to get professional help.
The Baker Tree Services team can verify the presence of SLFs, identify potential host trees on your property, evaluate the severity of the infestation, and recommend effective treatment options.
Contact us today to schedule an inspection and develop a plan to protect your landscape.
Sources and References
- Journal of Integrated Pest Management – “Lycorma delicatula (Hemiptera: Fulgoridae): A New Invasive Pest in the United States”
Peer-reviewed article documenting the spotted lanternfly’s biology, host range, and management following its first U.S. detection, providing the foundational scientific reference on the pest.
https://academic.oup.com/jipm/article/6/1/20/2936989?login=false - University of Maryland Extension – “Spotted Lanternfly in Home Gardens”
Extension resource for homeowners covering spotted lanternfly identification, life stages, plant damage, and control methods for residential landscapes and gardens.
https://extension.umd.edu/resource/spotted-lanternfly-home-gardens/ - Pennsylvania Department of Agriculture – “Spotted Lanternfly”
State agency hub covering the quarantine, reporting requirements, permits, and management guidance for the invasive planthopper first found in Berks County in 2014.
https://www.pa.gov/agencies/pda/plants-land-water/spotted-lanternfly - Penn State Extension – “Spotted Lanternfly”
Extension portal aggregating identification, life cycle, and control information along with webinars and homeowner guidance from the state where the pest first established.
https://extension.psu.edu/spotted-lanternfly - Penn State Extension – “Spotted Lanternfly Management Guide”
Comprehensive publication detailing identification and life cycle, quarantine and distribution, host range and damage, and management options for the spotted lanternfly.
https://extension.psu.edu/spotted-lanternfly-management-guide