[MichelleC]

Harvsted a few early nantes carrots and found the maggot just starting its feeding frenzy. It hasn't managed to get any further into the carrot. Should I pull up the rest before more damage is done? Also is there a difference between the cabbage root maggot and this?   

[JayG]

Time to look up some carrot recipes (as I think you've guessed the problem doesn't get better the longer you leave them.)

Carrot fly and cabbage root fly are different beasties; carrot fly is best prevented by either growing your carrots with a 3' barrier around them or the whole crop at a similar height above the surrounding ground because the flies are actually rather poor fliers. Covering with Enviromesh is probably the most foolproof solution.