The first thing I would do if I were you is squish them by hand, give them a good blast with the hose to dislodge them (and then squish them into the ground) or spray them with water that has a very little bit of mild dish detergent in it. (The detergent is alkaline and will kill any soft-bodied insect.) If you use the soapy water, I would follow it with a blast of fresh water so no soap residue remains on your leaves.
You could also buy and release a tub of ladybugs. Once they've finished feeding, they'll go elsewhere.
For ideas on controlling them long-term through Integrated Pest Management, check out my hub http://hub.me/acO2O
Good luck to you!