Fruit IPM - Spotted Lanternfly
Spotted Lanternfly (SLF) is an invasive planthopper in the United States. Originally from China, India, and Vietnam, SLF was introduced, likely via a shipping container on a commercial boat. The first established population was found in Berks County Pennsylvania in 2014. It since has spread to Connecticut, Delaware, Indiana, Maryland, New Jersey, New York, Ohio, Virginia, West Virginia, and, most recently, Worcester County. SLF is an imminent threat to agricultural industry in the United States.
The timeline described is consistent with observations of SLF New England, climatic conditions may alter it slightly. There is one generation of SLF per year. Fresh egg masses resemble a lump of white sludge. As this dries, it appear as cracked gray mud. Nymphs have four instars, first, second and third are black with white spots; the fourth instar has additional red patches. Typically, fourth instar nymphs appear in July. In late July, nymphs mature into 1-inch long, 1/2-inch-wide adults, with black-dotted gray forewings and bright orange-red hindwings. Female adults lay eggs between September and November, overwinter to hatch the following year.
SLF has a wide range of host plants, including many commercial crops such as apples and grapes, though their preferred host is the invasive tree of heaven (TOH) (Ailanthus altissima). Using a piercing sucking mouthpart, both nymphs and adults feed on plant sap and secrete honeydew, a type of liquid waste. SLF often feed in swarms. Large numbers of adults on one plant can prevent the plant from photosynthesizing for a short time by covering leaf surfaces. Accumulation of honeydew on plant surfaces encourages colonies of sooty mold, which then block photosynthesis chronically. These two factors weaken host plants causing stress and localized damage to branches. However, SLF damage alone has not been observed to kill hosts, except for tree of heaven, grapevines, and black walnut saplings. This is because SLF adults tend to “move on” from non-preferred host orchards such as apple, maples, etc., after a few weeks.
Grapevines are the most preferred commercially grown host crop for SLF. Grapes tend to have more extended exposure to SLF, thus sustaining greater damage, have reduced winter hardiness, and die at greater rates than other crops.
Public perception of SLF may become a more important problem than actual SLF damage, as patrons of PYO operations may feel uncomfortable in an orchard with the large numbers of insects present during swarm feeding, even though SLF is not harmful to humans.
Note: Management strategies for SLF are in flux due to lack of research on this recent arrival to our area. Currently there is no established economic threshold or economic injury level for any crop. Information below may change as new data comes to light.
Determining SLF populations is difficult because they fluctuate seasonally (SLF constantly moves from host to host) and annually. However, a good indicator of site specific SLF susceptibility is how many SLF-preferred plants are in the area as SLF has been observed returning to preferred individual host plants consistently every year. Circle Traps (Fig 3) use a modified net funnel to catch SLF nymphs and adults as they crawl up tree trunks to feed. Funnels lead SLF into a jar or plastic bag where insects die. Circle traps are inexpensive and have been shown to reduce SLF populations without harming other animals.
Sticky Traps consist of a sticky band wrapped around the trunk of a tree. A wildlife barrier must be used to prevent excess non-target catch, like birds.
Both traps can be baited with methyl salicylate.
-Promote plant health. Most crops can withstand SLF if they are free from other stressors.
-Remove preferred hosts, especially tree of heaven.
-Destroy SLF egg masses. Less than 2% of egg masses are laid at a reachable height; nevertheless, scraping accessible egg masses into an alcohol solution or crushing them thoroughly reduces population next season. Look on/underneath preferred host trees, then non-preferred trees and sheltered areas, such as under rocks, siding, etc.
-Biocontrol agents: Although there are no recommended predators to release for SLF at this time, the predatory wheel bug, Arilus cristatus, and stink bug, Apoecilus cynicus, have been observed feeding on adult SLF in Pennsylvania. Creating habitat for these insects may help reduce SLF population. Birds and mantids also consume SLF.
-Two native fungal species, Batkoa major and Beauveria bassiana, killed large numbers of SLF in a PA apple orchard. B. bassiana was previously known to kill SLF in China, while B. major is known to infect several insect species in Europe, Asia, and the Americas. It is unknown if these fungi will keep SLF populations down consistently or if they will cause boom and bust cycles. Ooencyrtus kuvanae, a parasitic wasp released in MA as a parasitoid of spongy (formerly gypsy) moth, also parasitizes SLF eggs.
SLF is not a robust pest; Extension specialists agree it is easily killed by systemic and contact insecticides, and trunk injections. Ovicides, including dormant oils, exist for use on eggs. Toxicity ranges for contact insecticides, providing the grower with a spectrum of options depending on infestation severity. Typically, it is recommended to start with least-toxic effective options first, such as neem oil and insecticidal soap, which still provide significant control. For specific products, visit Spotted Lanternfly Management Guide (psu.edu). Although currently there are no pesticides labeled for use on SLF, their high susceptibility to almost any insecticide means that they are likely to die as secondary targets during sprays for other pests. Always read labels before use of any insecticide, follow all directions and safety precautions, and do not exceed recommended rates. Refer to the New England Tree Fruit Management Guide for specific materials and rates recommended for managing the organism or issue.
Note: This information is for educational purposes only and is reviewed regularly for accuracy. References to commercial products or trade names are for the reader’s information. No endorsement is implied, nor is discrimination intended against similar products. For pesticide products please consult product labels for rates, application instructions and safety precautions. The label is the law. Users of these products assume all associated risks.
Date: December, 2021
Author(s): Zoe Robinson, Taylor Sharfman, Elizabeth Garofalo, Stockbridge School of Agriculture, UMass Extension Fruit Team