I observed a couple of these on an evening primrose plant in my yard over the course of a few weeks two summers back. Never got a good ID but I think it's similar to Richard's spiny bug (below)
so I was thinking perhaps it was Chariesterus antennator (Bug Eric?)? Then I did a google search on that name and came up with this: Florida Featured Creature - Euthochta galeator
. What do you think?