This subgenus comprises the Graphocephala species with red stripes, of which there are six in the USA and southern Canada. Definitive ID sometimes requires precise measurements and is therefore not always possible from photographs. The easiest to differentiate is G. versuta, which has black inscribed lines on the top of the head (hence "Graphocephala", meaning "written-on-head").
The next two species are more green than red, or at most, equally marked green and red.
The rhododendron leafhopper, G. fennahi (7.3-9.0 mm), is the only one that feeds on that particular plant, and is the only one found on the Pacific Coast. The stripes are unequal, with the ones on the back being fainter. In addition, males have a distinct spine on the terminal segment (you have to lift up the wings to see this).
The northeastern G. picta looks very much like G. fennahi but is found on other plants and is somewhat shorter (6.9-8.7 mm).
The remaining 3 species (the widespread G. coccinea and G. teliformis, plus G. constricta from MS, AR and TX; 6.2-7.4 mm) all look much alike, but have somewhat different ranges.
G. coccinea varies much in color, from nearly all red with blue stripes to nearly all green with red stripes.
In the subspecies G. c. coccinea, confined to the Atlantic coast, males are 5.7-6.2 mm long, and females 6.7-7.3 mm. In the inland subspecies, G. c. quadrivittata, males are 6.6-7.6 mm and females are 7.2-8.4 mm.
G. teliformis, 7.2-9.1 mm long, usually (but not always!) has equally wide red and green stripes. Its eastern, western, and southern known range limits are somewhat constricted relative to those of G. coccinea. Areas where the latter is found, but not the former, include: the Atlantic coast; southern Georgia, Alabama, and Mississippi; Florida; northwestern Arkansas; eastern Kansas; northern and western Minnesota; and southern Saskatchewan and Manitoba.
[Information taken from Hamilton (1985) and comments by Andy Hamilton on various images.]
See also G. rufimargo, widespread in Mexico and reported from southern Texas.
Hamilton, K. G. Andrew. 1985. The Graphocephala coccinea Complex in North America (Homoptera, Auchenorrhyncha, Cicadellidae). Entomologische Abhandlungen 49(6):105-111.