Spot - and then smash - the Spotted Lanternfly

Adult Spotted Lanternfly, image by Daledbet from Pixabay.

Kentucky entomologists are asking people to be on the lookout for a pretty but destructive insect that could be using its piercing mouthpart to suck sap from a tree near you.

The Spotted Lanternfly (Lycorma delicatula) is a native of Eastern Asia that made its way to the U.S in 2014, when it was found in Pennsylvania. In Asia the Spotted Lanternfly (SLF) is controlled by parasitic wasps that aren’t found here. It has spread rapidly and was confirmed in one spot in Kentucky in the fall of 2023. It now is in six Northern Kentucky counties. Experts believe it eventually will be statewide. 

The insect doesn’t sting or bite, but heavy infestations may injure or even kill trees. Adult SLFs prefer to attack the Tree of Heaven (Ailanthus altissima), which is  a non-native invasive tree species. In the nymph stage, they attack more than 70 kinds of plants, including willow, maple, apple, walnut, pine, poplar and stone fruit trees, as well as hops plants and grape vines. The maples, which also face a potential threat from the Asian longhorn beetle, could be a special problem in Lexington, where a survey showed that 43 percent of street trees are maples. Because too many of one species puts our tree canopy at risk, Trees Lexington seldom plants or gives away maples.

In Pennsylvania they destroy commercial crops worth hundreds of millions of dollars annually. In Kentucky, they threaten vineyards, apple orchards, Christmas tree farms, hop growers and the state’s important timber industry.

When Spotted Lanternflies feed on plants, they leave behind a sticky, oozing residue called honeydew. This substance attracts other insects (which can make parks and yards unpleasant), causes mold growth, and further hurts plants. As honeydew ferments, it can take on a rotten smell.

The Adult SLF is a little over an inch long, with a pink-khaki color and spots and stripes on its wings. Young nymphs are black with white spots and older ones are red with white spots. The eggs are laid in masses of 30 to 80 and can be found from September to June. Initially the masses have a white coating that darkens to tan or khaki and often appears to be smeared mud. They might be on a log, but often are found on fence posts, cars, mailboxes. Because the masses “hitchhike” on firewood, car bumpers or railroad cars, humans are inadvertently helping them spread. The role of rail lines and highways is evident in the new sightings in places like Indiana and Tennessee that have been hundreds of miles from known infestations. To get a better idea what the SLF stages look like from eggs to adults, here is a link to a video of Ellen Crocker, a University of Kentucky Extension forestry specialist.

What can you do to fight this problem? The experts tracking the SLF’s spread ask you to be alert and report any Spotted Lanternflies or their eggs as soon as possible. Johnathan Larson, a University of Kentucky Extension entomologist, said the easiest way to do that might be to take a photo of the insect or an egg mass and send the image, along with the location and your contact information, to reportapest@uky.edu. If you are on Facebook, you may post a photo on the Kentucky Bugs page. You may also file a report online here. And finally, you can dip your suspected SLP in alcohol and take it to your local extension service office.

The spread of Spotted Lanternflies is unlikely to be stopped, but you can play a role in slowing it by killing as many as you can. Heavy infestations might require insecticides. But if you find a few, the PennState Extension, which has dealt with SLF problems for years, recommends scraping and smashing egg sacs, using tree traps, and swatting or stomping nymphs and adults.