PITTSBURGH — On a muggy afternoon on Pittsburgh's North Shore, it felt good to step into the shade beneath a leafy tree. The smell was sweet and a sound suggesting rain was made by the patter of white sticky droplets falling on and around me.
On closer inspection I noticed the thin tree trunk was covered with hundreds of bugs, so dense their black and white wings overlapped, and I realized the sticky sweet drops were coming from the bugs. I was standing in an insect infestation and the "rain" dripping on my head and shoulders was spotted lanternfly poop.
Beyond the ick factor, Lycorma delicatula is a persistent alien invader from China and Vietnam first seen in Pennsylvania near the Philadelphia shipping docks in 2014. The bug doesn't bite, sting, carry human disease or harm people — the psychological effects of defecation inundation notwithstanding.
But the bug's propensity to target high value forests and farmlands has made it a target of the state Department of Agriculture. Shannon Powers, communications director, said spotted lanternflies pose a potential threat to the fruit tree, plant nursery and timber industries. In 2021 the insect's range reached Pittsburgh. If it continues north into Erie County, Agriculture Department biologists warn that spotted lanternflies could destroy the region's vineyards. A 2019 economic impact study estimated that, if uncontrolled, the insect could cost the state $324 million annually with a loss of more than 2,800 jobs.
"Right now, the insects are progressing from the tiny, black-with-white-spots phase to the more visible red-with-black-spots phase before adulthood, when it becomes much more visible and begins flying short distances," said Ms. Powers.
Considered leafhoppers, the bugs don't travel far. But spotted lanternflies speed across the state at 70 mph hitching rides on cars and industrial vehicles. In quarantine zones including Allegheny County, commercial drivers are required to have an anti-spotted lanternfly plan and remove the bugs and their eggs before cross-county travel.
"The quarantine, which applies to those in industries other than agriculture or trucking, has been a very effective tool in raising awareness that the insect travels primarily with help from humans," said Ms. Powers. "The permit, essentially required for anyone traveling for business in and out of quarantined counties, helps ensure that travelers recognize the insect and know how to keep from transporting it to a new home."
More than 1.3 million Pennsylvania spotted lanternfly permits were issued to businesses in the state and across the country.
The insect's preferred food is sap from tree of heaven, a fast-growing exotic deciduous shrub that has spread beyond backyards and is now considered another invasive species. Spotted lanternflies can feed from 70 types of plants, but Ms. Powers said they have "a strong preference" for grape vines, fruit trees and species that are important to Pennsylvania's timber economy including maples, black walnut, birch and willow.
The bugs don't chew leaves, their mouth part is a thin rough protuberance that is poked through the bark. Infestations can be so dense that massive amounts of sap are sucked from the host tree. The insect's sweet white excrement, "honeydew," drips from the trunk and branches, raining into pools that are soon covered with a dark crusty mold. The host tree withers and dies.
Spotted lanternflies are not the state's most populous or destructive invasive species, but they impact 40 of the state's 67 counties. In Pittsburgh they thrive at the source of the Ohio River behind Carnegie Science Center, along the Allegheny River on the North Shore and in patches on the southern bank of the Monongahela River from the South Side to Duquesne.
Randall Hall, a member of the Hilltop Urban Farm project, has been keeping track of the bugs for years. The nonprofit agrarian group farms 23 acres on Mount Washington. One impact of the spotted lanternfly may be nearer than you think, said Mr. Hall. As close as the honey jar in your kitchen cupboard.
Mr. Hall is a professional beekeeper and owner of BeeBoy Honey. Last year, he noticed a subtle difference in the taste of his product and in other brands of local honey.
"In Pittsburgh we have very mild honey because there's such a mixed variety of food sources [for the bees]," he said. "It's very complex honey compared to other areas. This [unfamiliar tasting] honey, there was an astringency to it, a bitterness, salinity, a smoky flavor," he said. "I immediately knew something was off."
Initially, Mr. Hall didn't consider the involvement of spotted lanternflies. Few scientific studies had charted the invasive species' impact on other insects. With the assistance of the state Department of Agriculture, one study determined that pesticides developed to kill spotted lanternflies were not impacting bees, which are still struggling from multi-causal Colony Collapse Disorder. A subsequent study found honey samples contained no anti-lanternfly pesticides, but included traces of a chemical naturally contained in tree of heaven sap to deter predation. The study yielded no conclusions, but Mr. Hall said a tentative hypothesis was developed.
"In Pittsburgh, tree of heaven is everywhere in every neighborhood," he said. "Tree of heaven has a chemical protectant that circulates several layers below the outside bark, a bitter tasting chemical that makes most bugs and birds stop eating it."
Spotted lanternfly nymphs and adults, however, prefer the carbohydrate-heavy tree of heaven sap and can feed continuously.
"They eat so much, that's why they excrete large amounts of honeydew," said Mr. Hall. "Bees, wasps and anything looking for a free meal finds this sticky honeydew and eats it."
Honey bees seek nectar and pollen. Sweet energy-boosting nectar is produced by flowers to lure hungry bees, which also sip nectar directly from trees when they can get it. Protein-rich pollen is collected by bees to feed to larvae, but it is unintentionally distributed among flowering plants during pollination.
Back at the hive, the bees process what they've eaten into honey and store the food for other bees. The honey includes semi-digested nectar from flowering plants such as dandelions, clover, goldenrod and fruit trees. If the bees consumed honeydew excreted by spotted lanternflies that had splurged on tree of heaven sap, the plant's bitter predator repellant influences the honey's flavor.
Apiarists unknowingly bottled the honey with the unusual ingredient.
"It turns out, the honeydew itself is beneficial to bees. No negative effect," said Mr. Hall. "Eating [lanternfly] honeydew is good for them and it doesn't do anything bad to the honey, it just changes the taste. I'm used to really delicate stuff, so when I first tasted the honey... But I got used to it. It's just a different flavor."
Word is slowly spreading about the honeydew honey, said Mr. Hall, and it isn't hurting sales. In fact, one competitor in Philadelphia promotes it as another variety of honey.
"I don't think anyone would be offended by the flavor even if they knew it had lanternfly in it," said Mr. Hall. "They'd say, 'Wow! It tastes different."
John Hayes: jhayes@post-gazette.com.
