The Arboretum grounds will be CLOSED TO THE PUBLIC on SATURDAY, JUNE 10 for ART in the Garden.
By now you have probably become all too familiar with the latest invasive pest affecting the trees and plants of the mid-Atlantic region - the Spotted Lanternfly, Lycorma delicatula.
The insect is a striking and some might say quite beautiful invasive planthopper that is native to Asia, mainly China, India, and Vietnam. It has since become established in South Korea, Japan, and the US. Only first discovered in the US in Berks County, Pennsylvania in 2014, the insect has rapidly spread into much of Pennsylvania and the states of New Jersey, Delaware, Maryland, Virginia, West Virginia, New York, Connecticut, and Ohio.
What are invasive insects anyway? What does the term mean? An invasive insect is one that typically is not native to the area within which it is infesting and spreading. As a newcomer on the scene, the invasive insect is usually not eaten by native predators as it has not evolved with them to become prey. This fact enables the invasive insect to outcompete often benign, essential, and other non-invasive organisms as it has no natural environmental or living roadblocks to slow down its spread.
The Spotted Lanternfly Lycorma delicatula appears to be particularly efficient at spreading and is unfortunately destructive to many plants and trees in our area. Many local towns report this summer seeing lots of the strikingly spotted little gymnasts, (they vigorously hop to avoid threats) and can also fly for short distances before landing and slowing sucking the lifeblood (sap) from cherished landscape trees and plants.
The insects really get about though through movement of their egg masses. You see, adult females lay eggs contained in a tannish membrane on not only tree trunks but pretty much anything they can find, including mobile things such as your car, truck, or your neighbor’s camper. They also lay eggs on the sides of homes, rocks and piles of wood that may often be moved from place to place. Most likely they were first brought into the country as hitchhikers on material being shipped from far-off lands. Those little egg masses, which bare a vague resemblance to that other noxious invasive like the Gypsy Moth, contain upwards of fifty eggs. Usually deposited around this time of the year, the eggs, in their sealed membrane insidiously wait through winter, remaining warm, snug, and safe, and hatch come late spring.
Upon hatching, spotted lanternflies will go through several instar stages and suck sap from mainly herbaceous material early on. Initial instars are strikingly beautiful, tiny black creatures with what looks like a polka-dotted cloak. After getting larger throughout the early summer, the black and white instar begins developing orange/ red striations before beginning to transition to the tan and black polka dotted adults (while resting) that we’ve become familiar with. When hopping or flying, their red internal wings become exposed, and they could easily be mistaken for a moth.
At this stage, the young adults get to work sucking the juices out of many different common plants, but they are most often driven into a frenzy by the invasive Tree of Heaven Ailanthus altissima. Its not certain yet if this plant plays an integral role in the continued health, growth, and survival of the lanternfly. Some scientists postulate that they may ingest a compound from Ailanthus that can make them toxic to predators, but this is not fully certain yet. What is certain, however, is that adult lanternflies find Ailanthus to be their preferred host and in areas where the tree has become prevalent, you will see them completely infesting the trunks. Sadly though, Lanternflies are also attracted to many other fruit bearing plants such as grape vines, apple, and other fruit trees, and both native and ornamental thin barked trees like maples.
The Lanternfly is unfortunately not a particularly efficient eater, and this is clear when one notices the extreme amount of sugary sap (honeydew) released by them as they are feeding. The sap cascades below the tree canopies and covers the ground, trunk, and leaves with a shiny, sticky covering that often harbors its own dark inhabitants, mainly sooty mold. The buildup of this gooey mess can create quite an eyesore, especially when it gets onto cars and decks and outdoor living spaces. All the piercing and relentless sucking of plant juices of course damages the host tree as well, as it does not get the nutrients it needs and can wilt, become sickly and in some cases more susceptible to secondary fungal or bacterial pathogens and other insects.
The onslaught by the lanternfly in masse results in the weakening of the host tree and can lead to greater susceptibility to drought and other environmental stressors as well as increased insect (wasps love honeydew) and disease pressure. The insect has certainly caused lots of damage to many fruit crops especially evident in vineyards and orchards. Timber tree health and productivity can also be affected by this organism in addition to ornamental plantings.
What can you do? There are a few things you can do to try and slow the spread. Be sure to remove and destroy any egg masses you see in the fall and winter. Kill any adults you may see and report infestations. Thankfully, adults die off by December as they cannot survive the winter. You may also want to keep stressed trees well-watered and monitored for any other problems.