Spotted Lanternflies in the City of Easton
The spotted lanternfly (SLF) is an invasive planthopper (a type of insect) in the U.S. It is native to certain parts of Southeast Asia. It was first discovered in the United States in Berks County, PA in 2014. It has since spread throughout 13 counties in southeastern Pennsylvania, which the Pennsylvania Department of Agriculture has designated as a spotted lanternfly quarantine zone.
SLFs feed on the sap of plants and trees and, when there are high populations of them, they can cause significant damage. They feed on over 70+ species, including important forestry and agricultural crops. The preferred food source for the SLF is the Tree of Heaven (Ailanthusaltissima), which is also invasive and non-native. If the Tree of Heaven is located in and around your home, most likely the concentrations of the SLF will be much higher.
The SLF does not bite or sting and they do not feed on any building materials, but they will swarm in large groups on structures, telephone poles, cars, etc.
SLFs excrete a waste product called honeydew, a substance that is high in sugar, which when excreted onto any surface will start to grow a black, sooty mold. This mold can blacken all surfaces under an infested tree. It can also cover a tree's leaves, preventing the tree and other nearby plants from processing sunlight through photosynthesis. This cycle will slowly weaken a tree and cause its immune system to send out chemical distress signals into the environment, alerting additional insects of its vulnerability and causing diseases the tree would have otherwise been able to ward off.
The City of Easton's current policy on treating the spotted lanternfly is to treat street trees that were purchased and planted through grant-funded projects since 2017. These trees are under warranty and the grant programs require us to maintain and care for them for various periods of time after planting, typically between 1 to 3 years.
Because SLF is currently a regional issue, there is no federal funding available, and the City does not have the funding or capability to treat the vast number of trees and plants in the city. There is also no recommended method from the USDA or Penn State to treat them in naturalized areas.
The City frequently receives questions from residents asking why the state does not spray for SLF like it does to treat black flies. Compared to the common use of broadcast/aerial treatments for black flies, the spotted lanternfly is a completely different type of insect that may not respond to broadcast treatment.
Residents are encouraged to be vigilant in the removal of the Tree of Heaven on private property. If the tree is removed, the stump needs to be treated with an herbicide, or else the root system could put out new sprouts. The link below provides help in identifying the Tree of Heaven.
It is recommended that residents systemically treat those trees that have value and/or are a high attractant to the SLF. We can recommend licensed and insured local tree services that provide these treatments. A pricing schedule and a list of approved tree surgeons will be available on the City's website.
Types of Treatment
There are different types of systemic treatments based on whether you have a flowering or foliage/shade tree. These applications can last from 4 months up to 2 years depending on the active ingredient in the insecticide. Trees that are high attractants to pollinating insects (flowering trees) can only be treated with specific insecticides and at specific times during the growing season to prevent those beneficial insects from also being killed. Waiting for your flowering tree to complete its bloom time is recommended to protect your tree for the duration of that growing season.
Trees that are deciduous (just producing foliage) can be treated with other insecticides that can last up to 2 years within the tree's vascular system. These treatments are being advocated as the only successful and long-term method of treatment for your trees due to SLF. If no action is taken, most native trees and shrubs will likely suffer damage that could be severe and even lead to death.
For those trying to kill the SLF on contact or on building surfaces, please read the product labels for proper usage and safety. Using insecticides and household chemicals as a contact method of control can be unsafe to humans, animals, and insect life, particularly in heavy doses or through constant re-applications. If a large tree becomes infested, it will be nearly impossible to spray the whole tree. The contact method is only recommended for manageable control on small ornamental plants and shrubs or for SLFs that are massing on structures.
Please refer to local, state, and federal guidelines to help make choices on which treatments you may use since the SLF infestation has no single preferred or recommended option.
There are several natural contact applications available such as insecticidal soap, horticultural oil, neem oil, and pyrethrins (extract from chrysanthemums). However, many homemade recipes are not recommended as they can be equally harmful to the environment and pets. If you spray homemade or natural treatments while they are in the sun, you will likely burn the foliage and/or discolor surfaces. Learn How to Build a Spotted Lanternfly Circle Trap for a Tree (PDF).
The USDA and Penn State are still trying to understand the behavior of SLF. There are promising solutions being studied, including two native fungi that are known to consume the SLF. However, until a proven solution is developed we must use the control methods that are currently available.
City of Easton Conservation Manager Rob Christopher is available Monday through Friday from 8:30 am to 4:30 pm for advice, information, and guidance with helping city residents in treating their trees.
Visit the Easton Urban Forestry Facebook page for up-to-date information.
Penn State is the leader in researching the spotted Lanternfly and is the entity creating the standards and protocols for the industry. The City of Easton is following their lead and recommendations as are all neighboring townships and municipalities. Find up-to-date information through the Penn State Extension website.
The United States Department of Agriculture (USDA) is also providing up-to-date information and standards to follow in fighting the spotted lanternfly.
Another local expert in the field, not only for SLF but many other garden pests, is Penn State Extension Educator for Northampton County, Amy Korman.
Tammy Craig is the Regional Supervisory Plant Protection Quarantine Officer specializing in the spotted lanternfly program through the USDA/Aphis.