The preferred overwintering host of the Spotted Lanternfly is Tree of Heaven (Ailanthis), itself an invasive plant species. The Pennsylvania Department of Agriculture describes the potential damage:
In the spring search for the nymphs on smaller plants and vines. Fruit trees and grapes can be especially susceptible to damage and mortality under larger populations. As the year progresses the Spotted Lanternfly host choice will transition to trees. Trees can be afflicted with weeping wounds of sap on the trunks. Heavy populations can cause honey dew secretions to build up at the base of the tree, blackening the soil around the base. The largest colonies can produce large fungal mats at the base of tree. Increased activity of wasps, hornets, bees, and ants can be seen feeding on honeydew secretions and at tree wounds.