San Juan Worms should be in every flybox. Aquatic worms inhabit most waters especially red bloodworms. They are a very popular fly in Northern California USA.
SAN JUAN WORM FLY PATTERNS. Hook size 10 12 14 16 - $US each
Many fly fisherman scoff at the use of the San Juan because it is not an "insect" imitation. Some people consider this a controversial fly, mostly because it has the word "worm" in its name. If it was called the "San Juan Stretched Caddis Larva" it would have more adherents. What do fish think it represents? Does it matter? It is fished dead drift near the bottom of rivers. The San Juan Worm is a true aquatic earthworm. It averages about two inches in length, and lives in the silty bottom of the San Juan river. Many rivers in the Rockies hold similar species. Fly fishers often imitate this worm with a length of chenille tied to a smaller scud hook.
This red midge larva tends to be eaten in fast water, since it must be swept away from its home on the bottom. The larvae thrash about as they swim. Midge larvae vary dramatically from cream color to chartreuse to blood red. A great many imitations in the San Juan's local shops are supposed to be some variation of this insect. The San Juan Worm is an excellent pattern to use on Alberta's Bow, Oldman and Crowsnest rivers. Chances are, it will work on your home stream too! It can be fished as a trailing nymph, dead drifted tight to the bottom. Or for midge worms and smaller patterns it can also be fished with a greased leader. Worms occur in dense populations in many silty stream and lake beds. During times of floods, catastrophic drift can expose many worms to waiting trout. During these high water periods a San Juan Worm drifted along the bottom can be deadly. On local rivers "the worm" is a very productive fly during winter months.
If the water is not clear and you cannot see your target fish you will have to read the water to try and find out the best place to cast your fly. Large areas of the river will hold no trout at all. Trout are usually solitary feeders and can normally be found next to something solid like a big boulder, patch of weeds, or the river bank. They lie up in stretches of the river where there is a high concentration of food. Look for creases on the water surface. These are lines that normally run downstream. They are caused by bodies of water, flowing at different rates, colliding. Trout food is concentrated in and around these creases. There is often slack water by the river bank and fast flowing water a few inches away. This is why a lot of trout can be found near the bank. Boulders and weedbeds cause the water to speed up to as they get past them. A crease is formed between the fast and slow water that traps floating aquatic insects in the eddies. Fish the crease and providing the trout are feeding you will catch fish.
FISHING THE LAKE MARGINS
I love watching a good sized brownie, rainbow or grayling, just a few yards away from my fly, open it’s mouth and inhale my nymph. Learning how to accurately cast and drift your flies to the right spot helps. I was fishing on my local lake one late season afternoon. There was no hatch yet. All the action was under the surface but most of the local angles were using streamers cast far out from the bank, with poor results.
I was stealthily stalking the windward banks looking for fish that were cruising along the marginal shelf about three feet out. When I caught sight of movement I tied on a bloodworm fly and dropped it into their path. On that day the trout were on the prowl for red food. I had several fish all caught on the same bloodworm fly pattern.
The movement in the water of the two unattached fibrous ends are irresistible to hungry trout. The artificial fly looks alive. It is also initially soft in the mouth until the hook bites. Do not hesitate to cast into the lake bank edge, particularly if there is a profusion of overhanging tree branches or shrubs. Good sized trout like to lie up in shallow water if they feel safe from areal predation by fish eating birds. They can then concentrate on looking for food passing them in the current. I caught a 2 1/2lb trout on my last trip by drifting a team of blood worms along the edge of a clump of water Lilly pads. The trout were resting underneath them, using them as a protective shield.
I do not normally fish bloodworm imitations but when I spooned the only Rainbow Trout I had caught after two hours fishing on a reservoir. What I found were a few buzzers but a lot of bloodworms. I took off the buzzers, gold ribbed hares ears and pheasant tail nymphs I had been using and replaced them with a bloodworm buzzer on the point and a red San Juan Worm on the dropper. My next drift was a revelation. My rod bent over and the fish dashed around the boat and off it went nearly emptying my reel. Several long runs later and I landed a fine fin-perfect rainbow. I had great fishing success over the next hour until a thunder storm cut short my fun. Dave my fishing mate in the boat had no success during the same period. He did not bring any bloodworm patterns and I had no spares. The moral of my story is always be prepared and have a fully stocked fly box. When you catch a fish find out what they are eating and change your nymphs to match - Mark King