Spotted Lanternflies in July 2023

Spotted lanternfly juvenile insects on grapevine

By Daniel Barringer, Preserve Manager.

Still here. While the invasive insect pest spotted lanternfly (Lycorma delicatula) may not still be here in as high densities as when the population first exploded after their arrival in Pennsylvania, they are very much present. I have seen the first of the adults already this year, but in July most were 3rd instar juveniles like these photographed on grape vine on July 19.

You might guess when you see this many insects in one place that they are having an impact, and these appear to be. We see these immature insects on grapevine, Virginia creeper and black walnut. The most notable impact can be seen on the leaves at the tips of branches of black walnut that turn yellow and flag as the branch dies back. A few black walnut trees have declined and died though many survive here.

Though not strong flyers the adults can be found on a wider variety of species and will feed on the sap of many trees. We see impacts on silver and red maples, for example, when sooty mold forms on the exudate from the lanternfly’s feeding—the sugar from the sap they consume makes a good food for the mold. These populations appear to be here to stay.