Larvae on plant roots can be any number of insects. Root maggots are most commonly from weevils that go by various names - bog weevils, corn weevils, bean weevils, etc. or the larvae of a fly type insect.

Dave

Great! More bugs. That's just what I need :). Is there something I should use on the soil to kill these?

There are any number of controls available for root maggots - both organic and synthetic. But the most effective method is prevention - keeping the flies away from the soil so they can't lay the eggs in the first place. That means things like floating row covers, mulch, yellow sticky traps to trap the flies, good fall garden hygiene to destroy any unhatched pupae, etc. Then there are things like beneficial nematodes, Diatomaceous Earth, and soil drenching chemicals (last resort).

The flies emerge from the soil in early spring and once they mate they begin to lay upwards of 100-200 eggs in the soil at the base of the plants. If they can't get to the soil they can't lay eggs.

Dave

Are you sure those are not root aphids? Common on lots of things, including dandelions.