You can also put a screened cover or floating cover over the infested plants and release the ladybugs under the cover. Once they get the idea that there are easy meals in your garden, they might stay to breed, and once they lay their eggs on the plants, the larvae will do even more munching.
Be sure to learn what ladybug eggs, larvae, and pupa look like so you don't accidentally smush them or spray them with some kind of insecticide.
I often find ladybug eggs in apple and cherry tree leaves when the aphids start, and everything under the plum tree including the hammock and individual blades of grass gets covered with the pupae, And we have to tiptoe around until they all eclose. This is also when the warblers and virios make their rare visit in the plum tree along with the resident chickadees, nuthatches, titmice, and finches, so I think they are here for the aphids and maybe the ladybugs too (?).
