By Maggie Herrick, Restoration Gardener for the Pittsburgh Parks Conservancy
As the spotted lanternfly (SLF) becomes more of a household name in Allegheny County, their dispersal throughout Pittsburgh's parks system is continuously increasing. The Pittsburgh Parks Conservancy's Horticulture and Forestry team can attest to their steady population growth as we have encountered them more than ever throughout the past year.
Monitoring in Allegheny Commons, Riverview, August Wilson, Emerald View, Highland, and Schenley has yielded sightings of this pest in all of these parks. Our observations have followed the life cycle of the SLF. We've seen the progression through the four nymphal stages and then into adults. The adults are dying off after the first frost, and now we are in a phase of their life cycle that is crucial to our control efforts: the overwintering egg masses.
After training with the PA Department of Agriculture this summer, the Horticulture and Forestry team set up SLF traps in the previously mentioned parks and Frick Park and McKinley Park, primarily placed on the SLF's preferred host plant. These odd-looking contraptions consist of a mesh funnel with the larger end facing downwards and the smaller end tapering into a closed plastic bag. The unwitting leaf hopper makes its way forward up the tree, following the tapering funnel into the plastic bag, where it cannot turn around and escape.
Although these traps are not intended to eradicate spotted lanternflies completely, they provide a glimpse of the populations in their immediate areas and reduce them somewhat. For example, traps in some parks, such as Frick, McKinley, and Schenley, captured none or only one adult, while the two traps in August Wilson Park captured well over a hundred adults by the first frost. These observations have clued us to where we will focus more of our time this winter scouting for eggs.
During this time of year, while the eggs are the only living life stage of SLF, the traps are taken down to prevent damage from winter weather.
"So are we done with the spotted lanternfly?" was a common question park users asked as we collected the traps in December. The answer is "no," they are simply waiting out the season until the eggs hatch, and the cycle starts all over again. Their return will be in exponentially more significant numbers than we have yet to see in our area, and it's only a matter of time before we start witnessing the damage their voracious appetites can have on the plants they eat. Although their population will inevitably explode, and we will lose plant life due to these pests, we can help slow them down and minimize their destructive presence. But the time is right now, and we must stay vigilant for years to come.
In their lifetime, an adult female spotted lanternfly lays one or two egg masses around September to November, each containing upwards of 30 eggs. The egg masses are about an inch in size and look like mud or cement splattered on surfaces of just about anything, such as trees, rocks, bricks, firewood, patio furniture, vehicles, potted plants that were outside soaking up the sun during the warmer months, etc.
The movement of these materials to new areas aids this sneaky insect in gaining new ground - seemingly in the same style as a Trojan horse. We experienced this firsthand while collecting our traps for the season and discovered an egg mass stealthily placed on its underside. Unfortunately, this trap came very close to making it back to Frick Park and would have unleashed a horde of nymphs come spring.
The spotted lanternfly has fed on more than 70 species of plants, and among their favorites are grapevine, hops, staghorn sumac, maple, and black walnut. Without getting into any specific numbers, it is easy to imagine the devastating effect their unchecked populations have on many agricultural industries. As they feed, they cannot digest all the sap they have sucked from the plant and excrete the excess as a sticky substance called honeydew. This sugary substance encourages the growth of sooty mold. This fungal disease can coat entire plants and cause decline or even death due to inhibited ability of the plant to photosynthesize. There are also no predators that have liked them, although some birds and the always non-discriminatory praying mantis have been observed consuming them. They currently add very little to the local food web while consuming and outcompeting way more than their fair share. This action can wreak havoc on the balance between other wildlife and habitats.
If those reasons were not enough to prevent further spread, let me try a more personal and closer-to-home appeal. An infestation of these pests is highly annoying and gross. And that statement comes from a bug enthusiast who spends most of her time outside and seeking them out for cute pictures and amusement.
Imagine the trunk of the largest tree in your yard or neighborhood completely covered with spotted lanternflies. That image may be enough to make your skin crawl, but now on top of that, imagine the sooty mold caused by honeydew excretions covering your garden, car, and even your deck and patio furniture. And finally, imagine this same sooty mold and honeydew concoction attracting unwelcome guests such as yellowjackets and ants. Ask a resident of Eastern PA or any of the other Eastern states that have experienced these scenarios firsthand since the initial infestations began in 2014.
So, what can you do right now to help lessen the damage and spread of the SLF? First, familiarize yourself even more with all their life stages to confidently identify them. Then, report sightings to the Penn State Extension by calling 1-888-422-3359 or visiting their website.
Prevent unintentionally spreading them by frequently checking vehicles and any belongings that have been outdoors. But most importantly, get outside and start smashing. On your adventures out to our parks and surrounding areas, keep an eye out for them and squash on sight. They are faster than you may think and will jump forward or fall backward to escape. They are usually a bit easier to catch after a big leap, or you can try the water bottle technique seen here. Areas bordering railways are almost guaranteed to have populations, and "trees of heaven" are magnets for them. You won't have to look far for this invasive tropical-looking tree as it is widespread throughout North America. Identify it during winter by its bark that looks like cantaloupe rind, seed clusters that stay on the tree during winter, and easily breakable twigs that have a scent of burnt peanut butter. Most of us probably don't need another excuse to get out and enjoy nature, but helping to ward off destructive invaders is a new one to add to the list!
To learn more about this pest and report sightings, visit PennState Extension’s and the PA Department of Agriculture’s websites here: