Composting brassica leaves

My wonderful brassica crop was razed to the ground during the snow, and my allotment neighbour told me yesterday told me that the leaves make fab compost - only thing is, the crop had a severe case of whitefly, so will it be safe to throw on the heap, or does minus 14 not even kill these beggars? Many thanks, Jude.

Thanks DD, I'll do it tomorrow as those leaves are really starting to get whiffy!