Douglas G. Pfeiffer, Dept. Entomology, Virginia Tech, Blacksburg, VA
Spotted lanternfly, Lycorma delicatula (White) (Fig. 1), is an invasive pest that is being watched closely in many states – not only the states with current infestations, but also areas where the insect is likely to show up next, or those with the most vulnerable crops. The most vulnerable crop is grape, so this will be of interest to many readers here. Spotted lanternfly (SLF) was first found in southeastern Pennsylvania in 2014. It has been spreading ever since, and it turned up in northern Virginia in 2018. In Virginia, it now infests the entire Shenandoah Valley and parts of the Piedmont. In 2022 it was detected in two North Carolina counties (Fig. 2).
Spotted lanternfly overwinters in the egg stage, and eggs hatch in late April or early May (in Virginia). First adults appear in mid-July and begin laying eggs at the end of September. Eggs may occur in high numbers once populations are established locally. Eggs are laid indiscriminately on trees and various other natural or artificial objects. Egg masses may be conspicuous on vineyard trellis posts (Fig. 3). Masses may also be deposited on the inner (concave) surface of roll-formed steel posts when used as trellis posts. This will provide some degree of protection for egg masses in the vineyard. Nymphs will feed on grapevines, as well as a wide range of other hosts. In the late season, the host range constricts, and tree-of-heaven and grape are the favored two host plants. During the adult stage, there is a problem with continued immigration into vineyards, complicating control efforts. Growers should become familiar with the appearance and biology of this invasive insect, and be prepared to apply insecticides targeted against SLF. However, there is no need to spray for the initial presence of a few insects. Provisional thresholds developed at Penn State University are 15-20 nymphs per vine in the spring and early summer, and 5-10 adults per vine in late summer and fall. Be sure to notify your local extension agent when SLF is found in our area.