Just pick them off if there are only a few. If your not excited about handling them, put on rubber gloves and perform "surgery". We've also used a solution made of vegetable oil, dish soap, tobasco, and water. Spray it on the plants and on the bugs.
We get them regularly. We haven't had a potato in this yard for 15 years. They love to attack datura's also. Picking them off and dumping them in soapy oil water is the best way to get rid of them.
There is also the BT fix...a biopesticide product based on the bacterium Bacillus thuringiensis (Bt) is available. M-One™, made from B. thuringiensis ssp. san diego, is genetically engineered (read: geeks in lab coats producing scary stuff to potentially kill us all) and therefore is not allowed in certified organic production. Novodor™, contains B. thuringiensis ssp. tenebrionis, a form of Bt that is not genetically engineered. That one can technically be used in an organic scenario.