Scored a 16lber on a self tied Hellgrammite imitation in Jan 06. It looks like a dragonfly nymph on steroids. Here's the dressing:
Hook: Size 2/0 Dai-Ichi livebait hook
Body: thin lead wire or foil, built up to 4mm thickness, lathered with dubbed dark olive antron, build it till halfway down the bend of the hook
Head: Light brown cotton thread built upto 6mm thickness, varnished with clear lacquer
Winter is good for flyfishing, especially on Northern mountain waters, especially the Ramganga. The fish are there and feeding on abundant insect life due to clear water. You need to look for rocky water, not more than 2' deep, preferably with some evidence of weeds (plenty in winter and just after). Don't bother fishing slow pools. The best will be taken in broken water where they can't inspect the lure too closely. Dead drifted nymphs on a tight-ish line and fast stripped baitfish imitations (Green Clouser Minnow! Yeah!)
Don't use anything less than a 12lb fluorocarbon leader,
Other flies that work are Walker's Mayfly nymph, most beadhead nymphs, esp if theyre greenish.
Oh yes. Take a page from the British era books and buy some fly-spoons. If you can't get them anywhere, fix yourself one, or several: take a small spinnerblade (0-2). Fix a small swivel (carp rig swivels very good) with a good, small split ring and mount a straight shank single on the ring. Casts like a fly, catches like a plug. My best on flyspoon was 21lbs just after the rains on the Ladhya river, one of Jim Corbett's favourite fly rod rivers.
Hope above helps, Cheers