SLF stands for Spotted Lantern Fly, and last September, this column addressed the progress of the lantern fly’s march south from Pennsylvania where it was first observed in 2014.
There had been many reported sightings last year that proved the invasive insect, originally from China, was now well established in Rockbridge. As predicted, Rockbridge has seen a significant rise in its spotted lantern fly population this year. Up until summer of 2024, the Virginia Department of Agriculture and Consumer Services was asking citizens to report sightings. This monitoring effort was suspended last year and reports are no longer needed.
Most SLFs in Rockbridge are in the adult stage now, about an inch long, most often seen resting with its wings folded to give the bug a distinctive triangular shape, a dusky gray-orange color with black spots though there can be considerable variation in coloring as the bug matures.
The spotted lanternfly uses its piercing-sucking mouthpart to feed on sap from over 70 different plant species. It has a strong preference for Ailanthus trees (a.k.a. “paradise tree” or “tree of heaven”) but also gravitates to grapevines, maple trees, black walnut, birch, willow, and some other trees. Heavy feeding damage can significantly stress the plants which can lead to decreased health and potentially death. As SLF feeds, the insect excretes honeydew (a sugary substance) which can attract bees, wasps, and other insects. The honeydew also builds up and promotes the growth of sooty mold (fungi), which can cover the plant, forest understories, and anything else found underneath where SLF are feeding.
Pennsylvania’s experience with SLF thus far does not suggest we will see widespread death of trees, orchards, or other plants but very heavy infestations can negatively impact tree health. Orchards and vineyards are the most likely sites to experience infestations that warrant insecticide sprays.
The greatest impact of SLF for most people likely will be the sticky residue they can drop onto outdoor furniture, playground equipment, vehicles, and anything else situated under shade trees. This residue will likely necessitate repeated washing and scrubbing to keep the item clean.
While SLF will feed on and lay eggs on a wide range of tree species, their favorite is the Ailanthus and destroying Ailanthus trees is the best strategy we have at this point to limit the impacts of SLF. We cannot eliminate spotted lanternfly, but destroying Ailanthus will curb SLF impacts and presence.
Many landowners object to the use of any herbicides. Eliminating Ailanthus, Autumn Olive, and other invasive woody perennials solely by physical removal demands multiple cut-andremove efforts every year and new seedlings will constantly be reestablished. “Home remedies” such as vinegar, garlic salt, or petroleum products are not effective.
For resources explaining the life cycle of spotted lanternfly or for more details on killing Ailanthus trees and other problem weeds, contact the Rockbridge Extension Office at (540) 463-4734 or by e-mail to [email protected].
AN ADULT spotted laternfly. (photo from the Virginia Cooperative Extension website)
