The spotted lanternfly has the potential to infest over 70 species of trees and vines, but its preferred host is the equally invasive tree-of-heaven (Ailanthus altissima). You may also find this invasive pest on a wide range of fruit, ornamental and forest trees and vines, including grape, apple, birch, poplar, maple and walnut. Spotted lanternfly damages plants in three ways:
1) Sucking out the sap and weakening the plant so that its yield (ex.grapes) is reduced.
2) Secreting “honeydew” which increases the occurrence of sooty mold that blocks sunlight and inhibits photosynthesis - a vital process for trees and vineyard vines to grow and produce fruit and timber.
3) Stressing plants which allows other insects and pathogens to potentially damage and kill the plant.
They are also a nuisance when they hop and fly into people and aggregate in high populations. There is a lot that is unknown about this relatively new pest, but we do know that spotted lanternfly has the potential to cause severe economic and ecological damage to the urban landscape environment, agricultural industry and our native forests.
NJ Department Of Agriculture Page - an excellent page with a lot of detail. Note the tabs on the top of the page for the different sections https://www.nj.gov/agriculture/divisions/pi/prog/pests-diseases/spotted-lanternfly/