This common name refers to only one family.
These are pretty much always called Leafhoppers.
These widely varied terrestrial (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.)
insects sometimes accidentally jump into trout streams. I have heard of trout being selective to them, but it is not very common. Anglers often call them jassids.
They are very small and are best imitated on hooks sized 22 or smaller. They can be treated the same, from the angler's point of view, as the Membracidae
family of leaf hoppers.