Introduction
Spotted lanternfly (Lycorma delicatula, SLF) is an invasive insect that feeds on many plant species, including economically significant agricultural and horticultural crops, ornamental nursery plants, and trees. Despite its name, SLF is not a fly – it is a planthopper that rarely uses its wings to fly, preferring to use its legs to crawl and hop. Native to parts of Asia, including China, Vietnam, and Bangladesh, it was first discovered in North America in 2014 in Pennsylvania. It has since spread to and become established in several eastern states, including North Carolina, Tennessee, Georgia, and most recently South Carolina (see Cornell Integrated Pest Management: Spotted Lanternfly for an updated map of confirmed spotted lanternfly locations in the U.S.).
How to Identify Spotted Lanternfly
SLF egg masses contain 30 to 50 eggs and are relatively flat and covered in a gray, mud-like coating for protection. It is shiny when first laid but dulls and appears like dry clay as it ages. They are laid on many different surfaces, including plant material, rocks, vehicles, houses, trees, and almost anything else (Fig. 1a-b), which allows this stage to easily be transported from one place to another accidentally. SLF has incomplete metamorphosis, meaning eggs hatch into nymphs and go through several stages before becoming adults. Nymphs are small, starting out at about one eighth inch long and are black with white spots (Fig. 1c). They grow to about one-half inch long, the size of a nickel, by their final nymph stage when their color changes to black and red with white dots (Fig. 1d). Adult SLF are around one inch long and a half-inch wide with a black head and long black legs (Fig. 1e). Their body is mostly black, but females have yellow bands on the underside of their body. The front wings fold roof-like over their body and are gray with black spots and black stripes near the tips. Their hind wings are more colorful, with red, black, and white markings (Fig. 1f), but are hidden beneath the front wings when at rest. SLF adults are the only life stage with wings, and while they can fly, they are weak fliers and prefer to use their legs to walk or hop.
Figure 1a. The life cycle of SLF begins when adults lay egg masses, which appear as gray clay.
Pennsylvania Department of Agriculture, Bugwood.org
Figure 1b. Egg masses can be isolated or in groups.
Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org
Figure 1c. When eggs hatch, the nymphs are initially black and white.
Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org
Figure 1d. They acquire a bright red color during their last nymphal instar.
Sara Lalk, NC Department of Agriculture, Plant Industry Division
Figure 1e. Adults are winged.
David Coyle, ©2022, Clemson University
Figure 1f. And while they have bright red color on their wings, this is rarely seen.
Rebekah D. Wallace, University of Georgia, Bugwood.org
Life Cycle of the Spotted Lanternfly
SLF has one generation per year in North Carolina and likely a very similar life cycle in South Carolina (Fig. 2). Egg masses are laid in the fall and hatch in the spring. After hatching, SLF go through four stages, called instars, over about eight weeks before becoming adults in mid-summer. Adult SLF feed during the summer and early fall, and mate before laying their eggs in the fall.
Figure 2. Spotted lanternfly life cycle as known in North Carolina: Eggs (Sept–May), 1st instar (Mar–May), 2nd instar (May–June), 3rd instar (May–July), 4th instar (June–Aug), adults (June–Nov), egg-laying (Sept–Nov). One generation per year. Image by A. Ratcliff, NC State University, CC-BY- ND-4.0.
Host Plants
The invasive tree-of-heaven (Ailanthus altissima; see Clemson Extension Forestry and Wildlife Invasive Species Highlight: Tree-of-Heaven (Ailanthus altissima) for more information on this species) is SLF’s preferred host, which both nymphs and adults feed upon. SLF is a generalist herbivore that feeds on over 100 plant species, including several agricultural crops and trees important to South Carolina. Hosts include apples (Malus), plums and peaches (Prunus), grapes (Vitis), cucumbers (Cucumis), basil (Ocimum), blueberry (Vaccinium), black walnut (Juglans), maple (Acer), oak (Quercus), birch (Betula), willow (Salix), sycamore (Platanus), and many other woody deciduous species. Ornamental species, including roses (Rosa), forsythia (Forsythia), hibiscus (Hibiscus), and zelkova (Zelkova), can also be used as hosts. SLF typically does not use conifer species as hosts for feeding.
Signs of Spotted Lanternfly Damage
Nymphs and adults often feed alongside each other (Fig. 3a), sometimes in extremely high populations (Fig. 3b). SLF is a sap feeder and feeding damages the host plant by removing fluids from the plant. Typically, this feeding is a plant stressor that weakens the plant, though high levels of feeding can cause plant death. Early signs of feeding may include plant wilting, while later feeding damage may appear as branch or plant dieback. SLF produces copious amounts of liquid excrement called honeydew while feeding. Honeydew is a sticky substance that covers anything below feeding sites and attracts ants, wasps, and bees. Eventually, a dark fungus called sooty mold grows on honeydew (Fig. 3c), reducing a plant’s ability to photosynthesize, staining objects on which it grows (including vehicles and tree trunks), and is visually unappealing.
Figure 3a. Nymphs of SLF on a host plant.
Sara Lalk, NC Department of Agriculture, Plant Industry Division
Figure 3b. SLF adults on a host tree.
Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org
Figure 3c. Black sooty mold that develops on the leaves of a plant after SLF feeding.
David Coyle, ©2022, Clemson Extension
Economic and Ecological Impact
SLF has already had a significant impact on the agriculture and forest products industries in the U.S. According to a 2020 study, Pennsylvania’s agricultural industry loses an estimated $43 million statewide annually, with worst-case scenario estimates of over $99 million per year. Its forestry industry loses an estimated $153 million statewide, with a worst-case scenario estimate of over $236 million per year due to the damage caused by SLF.
In non-agricultural areas, SLF can be a significant landscape and nuisance pest. It damages ornamental trees through its extensive feeding and production of honeydew, which attracts stinging insects and promotes the growth of sooty mold. SLF is estimated to have a $2.6 billion impact on the ornamental plant industry of affected states.
The estimated impact of SLF on the fruit tree and grape industry was $915 million as of 2019, and there are likely risks for peach orchards in South Carolina, which is one of the largest peach producing states in the country (South Carolina Department of Agriculture FAQs: Peaches). Peaches are in the same family as apples, a known host of SLF (Fig. 3b). South Carolina is also home to dozens of vineyards that could be impacted, and native species such as muscadine are a known host. SLF feeding can kill grapevine, reduce fruit production, and increase management costs. For instance, from 2016 to 2018, the average cost of insecticides used by Pennsylvania vineyards tripled. SLF infested materials may face additional inspections and potential delays prior to being shipped, further impacting South Carolina’s agriculture, forestry, and horticulture industry.
How to Manage Spotted Lanternfly
It is difficult to manage SLF, partly because they are highly mobile and infestations typically occur in large numbers. Broad-spectrum insecticides (especially those containing bifenthrin or dinotefuran) are effective and will kill SLF, though these will also result in the mortality of other beneficial species. Many insecticides already used to control other pests can protect crops against SLF infestations. Insecticidal soaps have been successful for controlling SLF nymphs and adults, and horticultural oil can be used to kill egg masses. Egg masses can also be scraped with a knife or credit card into a bag or container containing rubbing alcohol, as this will kill the egg masses. Always read and follow the label on the insecticide container – the label is the law! Around homes and businesses, SLF can be managed as a nuisance insect by physically removing the insects, by swatting or stomping SLF or by vacuuming and emptying them into a bucket of soapy water. Biological control options are also being researched to aid in the management of SLF. Native generalist predators (e.g., praying mantids, spiders, birds) will feed on SLF, and two fungal pathogens were recently discovered that kill SLF, though these are not currently recommended for management. Research continues to optimize current biocontrol possibilities and to find new potential biocontrol agents from SLF’s native range.
Since SLF frequently congregates in large numbers on host plants, visual monitoring for infestations can be an effective way to detect populations. SLF prefers to feed on tree-of-heaven, and the male trees (which do not produce seeds) can be used as trap trees to help monitor or manage the pest. After removing female tree-of-heaven (which produce seed and can spread this invasive plant), male trap trees can be left behind to attract SLF. These male trees can then be treated with a systemic insecticide to reduce the pest population. Sticky bands may be added to help monitoring efforts by trapping the nymphs crawling on the host tree, but there are currently no baits available for attracting SLF to traps. If sticky traps are used, note that these can capture and kill non-target organisms in addition to SLF. Researchers have also developed lampshade traps, which encourage SLF egg laying and subsequently lead to the consolidation of many egg masses into one easy-to-access area that can then be removed and destroyed.
Preventing the Spread of Spotted Lanternfly
Since SLF management is complex and efforts to eradicate populations have not been overly successful, preventing and/or delaying the spread plays a major role in the control of this invasive pest. Any equipment or vehicles that have been in or near SLF-infested areas should be checked for SLF. The removal of potential host plants (e.g., tree-of-heaven) around agricultural areas or nurseries can be beneficial. If an insect is suspected to be SLF, capture the insect or take a picture (and kill it afterwards) and report it to your local Clemson Extension agent or to the Clemson Department of Plant Industry Invasive Species Program SLF reporting tool.
Additional Resources
- Don’t move firewood: https://www.dontmovefirewood.org/
- NC State Extension: https://content.ces.ncsu.edu/spotted-lanternfly
- Penn State Extension: https://extension.psu.edu/spotted-lanternfly
- Cornell Extension: https://cals.cornell.edu/integrated-pest-management/outreach-education/whats-bugging-you/spotted-lanternfly
- LGP paper: Spotted Lanternfly Management in Nurseries, Orchards, Vineyards, and Natural Areas in South Carolina and Georgia | Land-Grant Press (clemson.edu)
- APHIS website: USDA APHIS | Spotted Lanternfly
Originally published 03/23
