Parsnip Infestation

Hi,
Checking a wilted parsnip, I found that the root had turned brown and was infested with some small bugs. They are orange/brown in colour and not maggots or worms as they move readily on their legs.  I've checked my gardening books without success... can anyone advise what they are and how to deal with them ?

Could be cut worms.  Cut worms curl into a C shape when disturbed.

Only contribution I can make is that a few years ago the underside of a few of my parsnip plant leaves were covered with small torpedo shaped eggs - no idea which bug laid them - I destroyed all affected leaves, and the parsnips turned out ok.
Check yours out for something similar - hopefully it'll only be an isolated problem.