The Spotted Lanternfly: A Growing Threat to Trees

Spotted Lanternfly (SLF) adult.
Spotted Lanternfly (SLF) adult.

The Spotted Lanternfly (SLF), Lycorma delicatula, is a recently discovered invasive insect species that is attacking a wide range of ornamental and agricultural tree species in the Eastern United States. It is thought to originate in Southeast Asia and was first discovered in the U.S. in 2014 in Pennsylvania. Since then, it has spread to neighboring states, from West Virginia to Connecticut. It has been confirmed in almost every county in New Jersey - including Bergen County!

This insect is a significant threat to agricultural production and hardwood tree vigor in the United States. In addition, its voracious, indiscriminate appetite, large numbers, and relatively large size can create quality of life issues, particularly for those of us who like to spend a lot of time outside. 

SLF has six life stages: eggs, four nymph stages and an adult stage. Nymphs are smaller and wingless, while adults are large and can fly around, but all stages of this insect use piercing/sucking mouthparts to puncture trees and drink their sap. As SLF consume tree sap, they decrease tree vigor, making trees more susceptible to secondary stressors or infections. While few outright SLF-caused mortality events have been observed, the presence of SLF infestation can be the tipping point that pushes a struggling tree into an irreversible decline cycle. As such, they can be threats to large specimen trees in our community.

Additionally, as the insect feeds, it produces honeydew, a sticky, sugary substance which can attract stinging insects such as wasps and bees. The honeydew is also a food source for sooty mold, a black fungal organism which will colonize any surface that honeydew lands on including understory plants, cars furniture, etc.

SLF’s preferred host is the Tree of Heaven (Ailanthus altissima), another invasive species from Asia that was once planted as a street/shade tree but has now overtaken large swaths of land with its aggressive and relentless reproductive cycle. While it may seem beneficial that this insect is attacking another invasive, Tree of Heaven and SLF likely co-evolved together in China and thus are used to coexisting. More worrisome is SLF’s appetite for natives like grapevines, black walnuts, maples, and willows. In fact, it will feed on upwards of 70 different native plant species! Its potential for large-scale economic and aesthetic disruption should not be taken lightly!


SLF nymph.

What Can You Do to Help against the Infestation?

Follow New Jersey SLF Quarantine Ordinances. SLF is not yet present in large enough numbers in Bergen County to call for quarantine but following the guidelines when travelling to or from quarantined counties can help keep it that way. Inspect your vehicle, trailer, and any other outdoor items for SLF before moving them. Businesses are forbidden from, and individuals are encouraged to avoid, moving firewood out of these counties:

  • Visit the New Jersey Department of Agriculture website to learn more about the quarantine
  • Familiarize yourself with photos of various SLF life stages and inspect your own property for SLF. Destroying live insects, and egg masses, can help keep this voracious population down.
  • Consider removing all Tree of Heaven if practical. One line of research suggests that Tree of Heaven feeding may be necessary for SLF to complete its lifecycle. 
  • Report any SLF sightings outside of Quarantine Counties at SLF-plantindustry@ag.nj.gov 
  • If severe infestations are occurring, contact a tree expert to discuss options beyond manual insect removal (such as chemical, biological, or cultural treatments).

Jeff Pilot, Borough of Franklin Lakes Tree Specialist

Jeff, as the the Borough's Tree Specialist, administers the Borough's tree removal permit process, reviews tree removal plans in connection with soil moving and development applications, and provides advice to the Shade Tree Commission and Borough officials on tree-related matters.

10/13/2021