No pesticide is needed or recommended for treating Spotted Lanternfly, though you could physically squish any you want. (They are already present in almost all Maryland counties.) This is in part because no spray would be specific to this pest (it could harm other insects that the residues contact), and because more lanternflies could simply fly into the area after the current population was removed (if a treatment were successful). Topical sprays which kill insects on contact might not work as well since these insects tend to be pretty wary, moving out of the way or jumping or flying away if disturbed. If they are congregating on Tree of Heaven, their favorite host plant, that invasive tree should ideally be removed, as per the detailed recommendations in the Penn State reference material which that page links to.

Miri