A Diet of Worms

A Diet of Worms

A defense of the San Juan Worm in two variations

  • By: Chad Mason
The big rainbow made three runs to the center of the river and three times I felt the backing knot bump the stripping guide. I'd been fighting similar fish all afternoon and my wrist eventually seized in place with painful cramps. (Yeah, I know--life is hard.) The river had risen markedly throughout the day, due to increased releases at the dam upstream. I looked behind me for slack water where I could net the fish, and discovered that the river now covered my lunch rock and was nearly lapping at my camera, which was sitting on a boulder.Finally I eased the fat rainbow into a quiet place and slipped the net under him. After a quick tug of the hook, I held him briefly to remember him and then let him go. Several more wrist-busting fights would follow, until the "fly" at last fell apart. You may be wondering why I put fly in quotation marks. Peer pressure, I guess. The pattern in question was a San Juan Worm. If there were a Wittenburg Chapel of fly-fishing and I could nail my 95 Theses to its door, Thesis Number One would read: "The San Juan Worm, being an accurate imitation of a natural aquatic organism, should be acknowledged as orthodox in the canons of angling, and no longer be anathematized as a flyrod heresy." Of course, the ethicists might then rebuff: "Effectiveness is no foundation for a morality, nor is popularity with the masses; the ends do not justify the means." Right you are! So let us defend "worm patterns" not solely on the basis of their popularity or effectiveness, but on the grounds of their correspondence to the Law of Nature. The San Juan Worm and other "legless nymphs" have saved the day more times than I can recount. I've used them to catch trophy rainbows on Western tailwaters, brookies in the North Woods and hook-jawed browns from Midwestern spring creeks. There have been times, in fact, when trout seemed unwilling to take anything else. Worms, naturally Because the San Juan Worm works so well after a rain, many anglers--especially those who malign the pattern--mistakenly believe it imitates an earthworm washed into the stream. But this belief can be sustained only by overlooking two salient facts: 1) it would take a hell of a rain to wash a subterranean creature into a trout stream, and 2) all subsurface patterns work better after a rain. For example, although a husky black nymph will often perform well after a rain, no angler assumes such a nymph imitates a cockroach; they're imitating stonefly nymphs. Similarly, the San Juan Worm imitates an aquatic creature, not a terrestrial one. Aquatic worms live in all forms of fresh water--lakes, ponds, reservoirs, marshes, rivers and streams. Closely related to earthworms, aquatic worms belong to a class of annelids called oligochaeta. Aquatic worms are amazing creatures that can breathe through the walls of their bodies and regenerate lost body segments. The genus of particular interest to fly fishers is Limnodrilus. Limnodrilus feed on mud and small particles of plant and animal matter that collect on the bottom of a river or lake. The feeding worm will often posture itself head-down into the stream bottom, with its body protruding in the current. Feeding worms are highly visible to foraging fish, which may "grub" the worms from the bottom. Worms may also be dislodged by the current and drift downstream, especially after a heavy rain or during high dam releases. Fish will seldom refuse a drifting worm. Limnodrilus varies in color from light tan through shades of brown and red, and reaches a length of about two inches (5 cm). Its body seldom exceeds 1/16 of an inch in width (less than 2 mm). Life span is typically one to two years. Mating and egg-laying activity usually occurs from late summer through early fall. Because worms are active at this time, their imitations can be quite effective even in the low, clear flows that are not usually deemed ideal for fishing a worm pattern. Egg-laying may take place in mud, on rocks, or among vegetation. The best imitation of Limnodrilus, bar none, is the popular San Juan Worm. This is a wonderful pattern for beginning anglers and fly-tiers because it builds their confidence and enthusiasm for fly-fishing. Experts can also learn a trick or two that will improve this pattern. (See the in-line bead recipe.) In flowing water, the SJW should be presented near the bottom on a dead drift. In still waters, it may be twitched at mid-depth or allowed to settle on the bottom. Once on the bottom, creep it along painfully slow. Not Garden Hackle In addition to the San Juan Worm, I've had excellent results with the Rockworm pattern. Here again we are not dealing with low-level garden hackle. Depending on the color of body material used, the Rockworm can imitate two other aquatic "worms:" craneflies and the free-swimming caddis Rockworm (Rhyacophila). Craneflies are exceedingly common insects of the order Diptera, which also includes midges. In fact, an adult cranefly somewhat resembles a giant midge. I've heard them described as "daddy longlegs with wings," and the description isn't far off. Craneflies belong to the genus Tipula, which includes many species. The larval stage of the cranefly is a plump worm ranging from half an inch to a whopping three inches in length. Most common colors for the larva are cream, gray and light brown. Tied with corresponding colors, the Rockworm pattern perfectly imitates a cranefly larva. From the order Trichoptera (caddisflies) come the genus Rhyacophila, which includes more than 100 species in North America. Think of Rhyacophila as the caddisfly from Hell. The larvae are big, green and live off of other hapless aquatic nymphs. Unlike most caddisfly genera, Rhyacophila larvae do not build cases; they are free swimmers. These plump, green, worm-like larvae thrive in cold, swift waters, where they absorb oxygen through their skin and rappel down the sides of rocks on their own silk-like secretions. Reaching nearly an inch in length, the Rhyacophila larva is easily imitated with a green Rockworm pattern. Coffee Can Needed Thanks to Limnodrilus, Tipula and Rhyacophila, trout already subsist on a diet of worms. Wise anglers imitate them with flies, and not with squirming critters hoisted from a red Hills Brothers coffee can. Try the San Juan Worm and Rockworm patterns on a river near you--and don't worry about committing heresy in the process. Recipe: San Juan Worm (in-line bead) Hook: TMC 2487, size 12 Bead: 1/8" copper Thread: 6/0, tan or red (match body material) Body: Ultrachenille, tan or red Attach thread and wind to mid-point of shank. Attach a small strip of ultrachenille. Wrap forward over the ultrachenille, whip finish and clip thread. Apply a drop of head cement. Slide copper bead over hook point and up to eye of hook. Re-attach thread and build up a thread stop behind the bead. Wrap thread to rear of shank and add another strip of ultrachenille, leaving the tag end extending over the shank. Apply a drop of head cement at the tie-in point. Pass thread under tag end, and wrap thread to just behind the bead. Grasp the tag end of the ultrachenille and wind it forward over the shank tightly, creating a segmented body. When you reach the bead, wrap the thread tightly over the ultrachenille several times in the same place, then clip the tag end of the ultrachenille. Whip finish behind the bead, clip thread, and apply a final drop of head cement. Using a cigarette lighter, lightly flame the ends of the ultrachenille to taper it and prevent fraying.