Parsnip pest

[Odsox]

I have a parsnip pest that I have never seen before, and was wondering if anyone else knows for certain what it is.
The plants look perfectly fine but the roots have white grubs/larvae burrowed inside, about 3 or 4 to each root. They are very similar to vine weevil grubs but are slightly bigger and they make each root just about unusable.
I have Googled and the best I can find is the Carrot Weevil, but I can't tell if that occurs in the British Isles as most of the references are for America.
Has anyone else seen this before, either on carrots or parsnips ?

[Flo]

Parsnips suffer from carrot fly Sir.

[Odsox]

Thanks Flo, I realise that, but carrot root fly larvae are thread like and less than a millimetre in diameter and these are about 5mm in diameter and about 20mm long. Huge beasties like big vine weevil larvae.
I have never seen them before and I don't mind if I never see them again.

[Millymollymandy]

Size sounds rather like chafer grubs but I've not heard of them burrowing into parsnip roots before. Normally they eat grass roots although I do find some in my veg patch. Chickens like them.

http://en.wikipedia.org/wiki/European_chafer

[Millymollymandy]

And also, even though I'm a bug crazy person, those that are usually underground I know less about. Thanks for mentioning vine weevils as I hadn't realised their larvae looked like that. That'd be the 20 or so we found in a pot containing daffodils that I've just replanted. The chooks enjoyed their treat!