Length: typically 6.5-7.5 mm
As in other members of this family, the newly emerged nymphs of Aphrophora quadrinotata produce a mass "spittle" on the plant stem soon after hatching.
There are several theories on the function of the bubble mass. It may be chiefly a way of hiding the nymphs from predators, it may function to prevent the nymphs drying out, it may offer protection from fungal pathogens, or may play a role in regulating the pressure of the nymphs bodily fluids.
The numbers of Aphrophora quadrinotata in most areas seem to peak in July, but the species may still be active in September and even later.
Lateral view of Aphrophora quadrinotata. Note the interesting pattern in the eyes.
American Insects site