Lots of these nymphs on a Black Locust Tree. They look similar to Lopidea nymphs so perhaps these are nymphs of Lopidea robiniae?

Note: These locust trees are growing sideways out of a cliff just above the water line on the Chesapeake Bay. As a result, I can easily wade to the tree and collect specimens of the adults and the nymphs as opposed to actually climbing a tree. If anyone would like some specimens I would be happy to collect and send them at no charge.