Ah yes, beetle larvae from the scarab family. We call them curl grubs. Generally if there is lots of good plant matter in the soil, they shouldn't cause much trouble. We had them in large amounts in our garden at one point, but we have chickens which eat the excess. They only really caused harm to seedlings, so I'd dig the area to clear the big ones for the chickens and then the seedlings had the time to grow bigger before any left caused them too much harm. They are the big Christmas beetles, the smaller lawn beetles don't even bother the lawn and likely aerate it for us.
I think sometimes we're too quick to rush in and kill "pests" without realising that they have purpose as long as things are in balance.