Yup those are potato bugs, my mom grew rows and rows of potatos when we where kids - I've seen far to many of them for my likeing. Three ways to at least lessen the problem.
1 - get any adults as soon as you see them - they are hard shelled and have stripes - drown them
2 - the larva (which is what you are finding) - use a stick and a pail, knock them into the pail - do twice a day (this is faster then hand picking them all) and you won't get any to the audult stage
3 - when you are "swatting" the plants look for yellow/orange egg clusters on the underside of the leaves - pick those leaves and destroy them with the bugs
4 -(ok I said 3 things but there is 4) Make a mix of Diotomatios earth and cyan pepper (hot pepper) powder, place in a jar with holes in the lid and dust the plants when they are damp after a dew or rain this kills the larva - but not the adults