Sick Leeks

Yes you can freeze them.

I too have the same problem, last year I left  the leeks in the ground and peeledevery one,then squashed all the little blighters! The leeks looked dreadful when I had finished, but they soon ressurected and I had some lovely leeks at the end of it!

Having discovered the same issue with my own leeks I was chatting to one of the other plot holders about it, he passed on a snippet that one of the older chaps had given him as a tip (he says it works and predates easily available chemicals):
       Cut the foliage off the leek as far down as necessary to get below the moth grubs, this may be almost ground level depending on how far they have got into the leek, for some it may not be far enough, better to lose a few rather than all. Leeks being a collection of leaves effectively growing from a base will just keep growing.

It may slow them down a bit but I thought it worth a try and reduced all my leeks in stature quite dramatically over the weekend, I will report back any future success or failure.