Here is some information on these common garden pests. I know I have one variety where the adults like to chew small holes in potato, radish, turnip, mustard and sometimes cabbage when small. They will actually sometimes kill the cabbage seedling before it even emerges. The larvae are small and burrow into my potatoes. Thankfully they don't go very deep as a rule and can be peeled off when peeling a little deep.
In the one paper it mentions diatomaceous earth as a repellant.[/quote]