Well they start off black but this red ant lookalike has a prominent proboscis and dots on its abdomen that belie its true identity.
Among seed pods of a black wattle in remnant habitat in an inner city park
Two weeks back I spotted the black first (or second) instar and the (red) adult. I am making the risky assumption that they are the same species. http://www.projectnoah.org/spottings/893... This is called the pod sucking bug (and it was on pods) or the wide eyed bug.