If you don't use row covers, regularly inspect your plants and destroy any egg clusters you find, as well as larvae and adults. Also, place a heavy layer of straw mulch around your plants. Research indicates that the mulch inhibits the Colorado potato beetle's ability to actually find the plants, and the mulch acts as a microenvironment that encourages the beetle's natural predators, including ground beetles (which feed on larvae) and lady beetles and lacewings (which feed on both eggs and larvae).
You may also want to Plant coriander, dill, sweet alyssum, fennel, and cosmos around your potato patch to attract the beneficial insects. Also try planting potato varieties that mature before pest populations reach their height in early summer, such as Caribe, Superior, and Yukon Gold.
Surrounding your potato patch with a plastic-lined, V-shaped trench can also reduce the number of adults that reach your plants in spring. As they emerge from the soil and head for the plants, they'll fall into the trench, where they can't get out, and you can destroy them.