Two-lined spittlebug (Prosapia bicincta)
This tiny bug resembles a leafhopper but is in fact a closely related species called a froghopper, a kind of spittlebug (named for the foam the juveniles conceal themselves in for defense).
Adults are black, usually (but not always) with two red/orange lines crossing their wings, and bright red legs with black feet. They are 8-10mm long.
Nymphs feed on a variety of grasses, and sometimes corn; adults feed on holly and related plants. Prosapia bicincta ranges throughout the eastern United States, and is primarily notable for bedeviling farmers by damaging pasture grasses.