By Kenton Sumter – Maryland Department of Agriculture.
It’s been more than four years since spotted lanternfly (Lycorma delicatula) made its way into the Maryland Invasive Species Council’s Invader of the Month. While some folks may have lost track of it, this pernicious insect has unfortunately been very busy. From its original discovery in Cecil County in 2018, spotted lanternfly has become established in sixteen counties. Along with its invasion, spotted lanternfly has brought along a raft of problems including loss of vineyard crops, unbearably dense swarms, thick mats of sooty mold, and visiting stinging insects interested in feasting on lanternfly honeydew. Spotted lanternfly continues to be a problem for Marylanders, and there does not appear to be an end in sight. For this reason, spotted lanternfly has been chosen as MISC’s Invader of the Month for January 2023.
The spotted lanternfly is an east Asian insect that originates in southern China. In the United States it was first discovered in 2014 in Berks County, PA, though it is thought that the insect may have established sometime before 2014. From there it spread, coming to inhabit the entire Mid-Atlantic region. In Maryland, lanternfly was first found in 2018, in Cecil County. As of 2022 the lanternfly has become established across most Maryland counties.
Spotted lanternfly has six life stages. The first three nymphal instars are similar looking, only distinguishable by their increasing size. They are jet black with a smattering of white dots all over their bodies. These first appear in early May and continue to molt until they reach the 4th instar in June. Fourth instars are large with vivid red and white markings. Adults molt in July and persist until the first hard freeze of the year, usually sometime in mid-November. They are characterized by their spotted forewings and bright red hindwings, which are visible in flight. Egg masses are laid beginning in October and overwinter until they hatch the following May. Egg masses appear nothing so much as a patch of gray mud on plants and manmade structures.
Photos in order of appearance from Left clockwise: early instar nymph, 4th instar nymph, Lawrence Barringer, PA Dept. of Agriculture, Bugwood.org; adult, Lawrence Barringer, PA Dept. of Agriculture, Bugwood.org; egg masses, Richard Gardener, Bugwood.org.
Spotted lanternfly is a consummate invader. It readily invades crop fields, dense woodlands, city centers, and suburban communities. It feeds on a wide variety of plants in North America, 82 and counting! This makes it extremely difficult, if not impossible, to suppress. It is most frequently found on trees. Tree of heaven (Ailanthus altissima) is its preferred host. But it has a number of other hosts that it is fond of, including grape, black walnut, red and silver maples, eastern white pine, and willows. Keep an eye on these trees when monitoring your local spotted lanternfly. Lanternfly is a frequent hitchhiker and is frequently spread via trucks, cars, trains, and ships. Rail is a particularly potent vector of spotted lanternfly.
The danger posed by spotted lanternfly comes in two forms. The first is as an agricultural pest. Lanternfly is strongly attracted to grape vines. This means that the state’s vineyards have been placed under enormous pressure by swarms of thousands of hungry lanternfly. Feeding by these insects robs the vines of vital carbohydrates that they would otherwise sequester for winter. The honeydew that lanternfly produces also encourages the growth of naturally occurring sooty mold. This mold can grow over photosynthesizing greenery, reducing its photosynthetic potential or even killing it. This is important because Maryland’s wineries contribute roughly $3.16 billion to the state’s economy and employ 22,455 workers as of 2022 (wineamerica.org). Lanternfly can also infest nurseries and orchards, where the insects pose a risk by spreading sooty mold, harassing workers and visitors, and contaminating shippable products. Maryland’s horticultural industry, of which nurseries and orchards are a part, constituted 9% of the state’s economy in 2017. In 2018, the horticultural sector totaled $1.9 billion in sales, and employed roughly 25,000 workers (https://msa.maryland.gov/msa/mdmanual).
The second danger posed by spotted lanternfly is as a public nuisance. This is particularly significant for communities located in the most heavily infested areas. Residents of places like Hagerstown, Havre de Grace, and Perryville must all contend with massive swarms of lanternfly on their properties. The insects plaster the sides of homes, divebomb people trying to enjoy the outdoors, feed on gardens and ornamentals, spread sooty mold over vehicles and buildings, and attract stinging insects that feed on the lanternfly’s honeydew.
The Department of Agriculture, in cooperation with other state and federal agencies, has devised a few measures to help slow the spread of spotted lanternfly. First, a quarantine order has been put into effect for counties with reproducing populations of lanternfly. This quarantine has several knock-on effects. It requires that a business that moves regulated articles from or within the quarantined area acquire a permit. Permit training can be found at https://extension.psu.edu/slf-permit-training-md. It is only necessary for a single representative to take the training. Once complete, that representative is expected to train other employees on the identification and management of spotted lanternfly. Maryland residents can take the training, however it is not required by law.
The second measure is to destroy spotted lanternfly wherever it is found. This can involve physically smashing or trapping the insects. I have often been told that tennis rackets and fly swatters work well. Catching nymphs and adults in liquids such as ethyl-alcohol or a 50/50 mix of liquid dish soap and water, can be effective. Traps are effective at catching nymphs and adults. Adhesive traps can be purchased or crafted and placed on infested trees. Be wary that while adhesive strips seem low maintenance, anything can get stuck to them. Check your adhesive traps for stuck birds, mammals, and reptiles. Bag traps can be purchased or crafted and have the benefit of not trapping non-target animals. During the winter, egg masses are the name of the game. They can be located on trees and structures where lanternfly adults congregate. Egg masses should be crushed by pressing directly down on them. They can be scraped, however; they should then be deposited in a container full of alcohol, vinegar, or diluted dish soap. Egg masses that are scraped can potentially survive to hatch in the spring.
Insecticides can also be applied. Residents should be judicious when using insecticides. Consult University of Maryland Extension to determine the most appropriate insecticide to use. Such questions can be directed to https://extension.umd.edu/ask-extension. The Department of Agriculture is a pesticide regulator and cannot make recommendations as to what insecticides should be used against spotted lanternfly.
The Department of Agriculture asks that Marylanders report lanternfly sightings to our online survey at mda.maryland.gov/spottedlanternfly. It is especially important that residents keep their vehicles as sanitary as possible. Lanternfly is a notorious hitchhiker. Try your best to remove all lanternfly life stages from your vehicle before you travel. The state does employ a small treatment program that targets high-risk properties associated with new infestations, and transportation and agriculture businesses, however; we are not able to treat most residential properties. Residents will need to pursue management options on their own initiative. Together we can all work to slow the spread of spotted lanternfly!
- For more information visit our website at mda.maryland.gov/spottedlanternfly.
- For tips on management and identification visit UMD Extension at https://extension.umd.edu/resource/spotted-lanternfly-management-residents.