Moving from Baltimore to Philadelphia, I came to realize two absolute truths: city squirrels are fearless and will break into your apartment to steal your avocados, and Philadelphians are aggressive towards their bugs. In regard to the latter, I was walking to my first rotation lab in CTRB when I noticed the ground leading to the main entrance was littered with hundreds of insect carcasses. Sitting outside for lunch later that day, I quickly realized why. Everyone seemed to be going out of their way to violently stomp, squash, and kill these bugs en masse like a bizarre game of whack- a-mole. I passed it off as a quirky Philly thing. Now, a year later, I’ve joined in on the game and celebrate every successful squish (with only a twinge of guilt).
The spotted lanternfly (Lycorma delicatula), which is more closely related to the cicada than a fly, drives Philadelphians crazy, and rightfully so. At first glance, they are actually quite captivating. Their translucent forewings, speckled with Dalmatian-like black spots, are illuminated like a lantern by a second set of brilliant red wings nestled underneath. You can spot a flash of color as they fly clumsily through the air or hop lazily at your feet. They are perhaps best described by one Philly Reddit user as, “drunk little airplanes.” These planthoppers are well-traveled, too; native to regions of China, Taiwan, Vietnam, and India, they invaded South Korea in 2004, Japan in 2009, and purportedly hitched a ride on a stone shipment from China to the U.S. in 2012. Since then, the first U.S. infestation was reported in 2014 in our very own backyard - Berks County, Pennsylvania. Today, there are established populations in over 26 Pennsylvanian counties, Delaware, New Jersey, and Virginia, with sightings in several bordering states. And of course, they are everywhere in the city (not even Chipotle is safe).
The pesky spotted lanternfly may seem harmless compared to the West Coast “murder hornet”, but they threaten to destroy industries worth $18 billion and are being called by some as the worst invasive species the US has seen in over 150 years. It all starts with their appetite. Lanternflies possess needle-like mouth-parts that can pierce into nutrient-rich, sap-containing plant phloem. Inefficient metabolizers with an insatiable sweet tooth, these bugs must ingest large quantities of the sugary sap throughout their entire lifecycle to secure enough nutrients for development and reproductive demands. The resulting depleted phloem leads to weakened plants with oozing wounds and wilted branches, and their sticky excrement (aptly named, “honeydew”) promotes sooty mold growth that causes permanent damage to their hosts. Perhaps fittingly, their preferred meal is also a destructive invasive species from China, but one that is widespread and abundant across North America: The Tree of Heaven (Ailanthus altissima). Yet, it is their promiscuous eating habits that are key to their destructive nature and set them apart from other invasive pests. Spotted lanternflies enjoy a wide host range of over 70 plant species, including fruit and hardwood trees, grape vines, and hops. These crops are vital to the nation’s economy and directly threaten Pennsylvania’s agriculture, wine, orchard, wood, and craft beer industries, to name a few. A 2020 Penn State report estimates current damages to Pennsylvania’s economy at $50.1 million annually with a loss of nearly 500 jobs. If lanternfly populations spread to all 67 counties, the impact could be closer to $554 million per year with approximately 5,000 jobs lost [1]. Needless to say, these bugs mean business.
A spotted lanternfly posing for a photo with the Center City skyline, caught at the Perelman School of Medicine campus. Photo by Sarah Campbell.
The Pennsylvania Department of Agriculture is doing everything in its power to slow down the spread of the spotted lanternfly and mitigate its imminent damage. Part of what makes this invader so insidious is its ability to travel with ease. An adult female can lay columns of 30-50 eggs on almost any smooth surface, which are then covered by a protective grey putty into a single egg mass. The inconspicuous color and shape make it very easy for egg masses to go unnoticed, say, on a slab of stone shipped across continents (sound familiar?). Adults can even hop on and cling to moving vehicles, potentially crossing into unchartered territories. In an effort to impede their travel plans, a quarantine was established in 2014 across all infested PA counties to restrict the movement of bug-friendly cargo between businesses, but this zone has continued to expand. Other containment strategies include host tree removal, scraping egg masses from infected surfaces, wrapping sticky traps around trees, and insecticide treatment. Unfortunately, these efforts are unlikely to keep up with the pace of lanternfly expansion in the long run.
Is there a light at the end of the tunnel? Well, maybe not a light, but definitely a lanternfly and a brighter future, nonetheless. In fact, the answer to fight this pest may be as simple as joining forces with its native enemy. With no natural predators in the U.S., spotted lanternfly populations are expanding at alarming rates. But, back home, lanternfly eggs and developing nymphs are food for parasitoid wasps that keep populations in check. Scientists hope to introduce lan- ternfly-killing wasps that are native to China to help combat the issue, employing a method called classical biological control. The USDA is currently studying the behavior and host specificity of two Chinese parasitoid wasps, Dryinus browni and Anastatus orientalis, to ensure the safety and efficacy of their release into the wild and avoid an ecological nightmare [2]. Back where it all started in Berks County, PA, reports of two dinct fungal pathogens capable of killing spotted lanternflies have researchers optimistic about another natural remedy [3]. There’s also an exciting new training program at our very own PennVet that seeks to utilize dogs’ powerful scent to track down spotted lanternfly egg masses [4]. Be on the look-out for one of the future trainees, a young German Shepherd named Lucky, who is set to become Pennsylvania’s first Spotted Lanternfly scent detection dog.
Ultimately, it may be too late to fully eradicate this insect invader from our shores, but current management strategies and ongoing research could make our fears a thing of the past. So, what can you do to help? Stay informed, report sightings, check your car before driving, and most importantly, take this advice from the PA Department of Agriculture: “Kill it! Squash it, smash it... just get rid of it.” Happy hunting!
For more information, check out the PA Department of Agriculture
To report a sighting, especially if you are outside of the quarantine zone, call 1-888-4BADFLY.
References:
Amy Duke. October 2020. Scientists Examine Potential Economic Impact of Spotted Lanternfly in Pennsylvania. PennState Extension.
United States Department of Agriculture. Otis Laboratory Accomplishments 2018.
Eric H Clifton, Louela A Castrillo, Andrii Gryganskyi, and Ann E Hajek. May 2019. A pair of native fungal pathogens drives decline of a new invasive herbivore. Proc Natl Acad Sci U S A. 116(19):9178-9180.
Curt Harler and Hannah Kleckner Hall. September 2020. Novel canine scent detection program holds promise in PA’s fight against Spotted Lanterfly. PennVet, University of Pennsylvania.
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