My second crop, planted at New Roots Farm where I volunteer, is a different story. There I planted three rows, each nearly 100 feet long. New Roots is an organic farm, so I've used mainly cultural controls: the potatoes were planted in a different field from years past and I check the plants once a week for beetles. Yesterday I walked the rows plucking off (well, squishing) hundreds of Colorado potato beetle larvae and adults. It was not a pleasant task. The larvae are really disgusting.
An adult Colorado potato beetle, roundish like a potato and striped
Colorado potato beetle larvae
The Colorado potato beetle is voracious and difficult to control. Crop rotation may work if you can plant your crops 1/2 mile apart. Obviously, not realistic. Planting every other year helps a little, but not much. Hand picking the beetles and larvae works for small gardens. Pesticides (organic or otherwise) are not that effective either. Covering the plants with row cover after planting might work, but what if a few beetles get under the row cover. Another option is to grow early maturing potatoes (the plants mature before the larvae are most active), but those are not good as keepers.
I am fortunate thus far not to have the beetles in my home garden. This is only the second time that I've grown potatoes here so likely the beetles have just not found my spud plants yet. New Roots has grown potatoes for many years and the beetles are well-established there. Colorado potato beetles have now surpassed Japanese beetles as my least favorite pest. At least with Japanese beetles I only have to deal with the adults (I leave the underground larvae to the moles).
Given my experience growing a large crop of potatoes, I have no idea how potatoes are grown in this country. Likely commercial growers are using a ton of pesticides. I'll need to learn more from organic growers, even they need to use some organic sprays. Maybe I will just east fewer potatoes.