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Why tie a Gilly Gaddis? See https://youtu.be/FdH8C_w94lc Image Caption: Gilly caddis backlit by the setting sun -- A time when these larva commonly drift. Introduction Free-roaming larva from the Net-Spinners (Hydropsychidae) and Rock Worm (Rhyacophilidae) caddis families vary widely in how many gills line their abdomen—from none to a thicket of gills. The Gilly Caddis imitates those larva that have common gills. The Gilly Caddis imitates both these caddis families because they have a similar size, coloration, profile, life style as well as a dawn and dusk behavioral drift. The Gilly Caddis pattern is tied slim to help it sink to the stream bottom where the heavy beads near the hook eye make it tend to drift head down. The fly is tied using an "in the round" style—popularized by Charles Brooks in his 1976 book "Nymph Fishing..." This style makes a fly with a round symmetry that shows the same gilly abdomen look to the trout even if the fly is twisting on the leader as it bottom bounces downstream. Thus, a Gilly Caddis constantly projecting its fuzzy white underbelly as it fly drifts along signals a near-universal sign of vulnerability to predators-including trout. Besides behavioral drift, the life style of these caddis families also promotes catastrophic drift. Hydropsychidae dwell in net-covered retreats but are exposed to drift as they freely move about foraging on the rocks outside of that cover. They are also known to fight each other to occupy the same retreat which leads to the loser being forcibly ejected from the retreat and possibly on into the drift. Rhyacophilidae make no retreat at all and when foraging out in the open can likewise be swept away at anytime. In addition, scientific studies find that caddis larva can be washed into the drift during floods-- as well as during drought when they seek deeper water. And so on. The point is that the life activities of these caddis larvae along with their preferred fast flowing-water habitat promotes drift at any time. As such, caddis larva are an important fish food for the daytime fisherfolk to imitate without having to arrive early for the dawn behavioral drift or stay late for the one at dusk. Lengthwise, these caddis families overlap in the 12-18mm (1/2" - 3/4") range when mature (Hafele & Roederer, 1995, "Aquatic Insects..." Based on a Tiemco 206BL hook, this length translates to a size 10 -16. The 206BL is used because even a size 10 hook can to take 1.5mm beads (see note in recipe). This feature allows putting small diameter beads on the shank to imitate the thin dark thoracic plates and head found on the diminutive 1.5-3mm tube-like profile seen in the slimmer species of these caddis families. The ratio of thorax+head to abdomen length runs around 1/3 for Hydropsychidae to about 1/4 in Rhyacophila—which translates to using three 1.5mm beads on a size 10-12 hook and two beads on a 14-16. Coloration of these caddis families is often a shade of green: as expected for larva called "green rock worm." The green color varies from emerald to chartreuse on to olive. Also seen are brown, tan, cream or gray larva. Both caddis groups show a segmentation denoted by a color variation that can be combined with a variable diameter pearl-necklace looking segmentation. As always, screen your stream to see the caddis look that you need to imitate. Recipe Hook: Tiemco 206BL, size 10 to 16 Bead: Slotted black or nickel tungsten 1.5mm beads. Three beads on the size 10 and 12, and two beads on the size 14 through 16. On each bead, the slot is oriented towards the rear. NOTE: only some 1.5mm beads have a hole large enough to slide onto the hook. Beads from www.wholesaleflycompany usually do the trick Thread: Nano-Silk 30D to match abdomen chenille color Tail: About ten barbs from a white CDC puff feather Abdomen: Semperfli micro-fritz chenille in chartreuse, olive, brown or tan Gills: White CDC plume feather—its best if the stem nears 50mm (2") long. The length is needed because the stem thickens near its base & can mask the abdomen. The barbs are trimmed to about 2 mm length on both sides of the stem Ribbing: Small size wire; color to match abdomen or use a darker wire for a ribbing effect Assembly of the Abdomen: wind the chenille side by side forward to the last bead and cut off; then the trimmed CDC plume, followed by the ribbing, are wound forward in an open spiral and tied off at the last bead. Turn the hackle pliers as you wrap to keep the feather perpendicular to the abdomen Legs: The legs are made using say 10 barbs from a brown CDC puff. These barbs are placed between split threads, spread out a bit and spun into bit of a spiky yarn. Then wind the spiky thread forward between the beads and end up just behind the hook eye. Whip finish there. I like to leave the legs long to add action to the fly. Fishing the Gilly Caddis Both Hydropsychidae and Rhyacophila larva let loose of the bottom on a regular basis at dawn and dusk and drift along. Besides this behavioral drift, there are also man-made and natural causes leading to these larva to drift. For one, Hydropsychidae larva are known to fight over which one gets to use the a net-lined retreat. As the video clips in the Gilly Caddis video show, these fights lead to one of the larva being forceably expelled from the retreat and at that point could easily loose grip and drift away. I developed this fly for the Arkansas River where in the warmer months there can be 100's of rafts rubbing the bottom and the sides of boulders each day. This leads to catastrophic drift when these omnivorous free-living caddis, out grazing and hunting, are exposed to this rubbing, as well as having the entire net retreats along with housed caddis torn off the rock surface. Another man-made drift is produced by fisherfolks wading boots as they move across the bottom to fish. While walking on the bottom inadvertently leads to drift, intentional scuffing of the bottom to induce drift this is colloquially called the San Juan Shuffle. The point is that in many rivers, some caddis drifting is ongoing all day long—not just dawn and dusk. So I often use the Gilly Caddis both as a dropper and as a point fly --when fishing the fly on a rocky stream bed--because I use a bottom-bouncing presentation made with the rod held downstream low to the water surface. the off and on hang up of the point fly as it bounces downstream acts to pulse the leader up and down as well as dropper fly--in effect jigging it. This jigging presentation is particularly effective in the days before these caddis groups pupate--when the larva become notably more active. Of course, the larva become unavailable to trout once they start pupation. Both these caddis groups almost exclusively live in running water, so the Gilly Caddis is best fished in rocky riffles or at the current transition at head of a pool. On the Arkansas River, the Hydropsychidae caddis larva start to drift in the early spring (per Greg Felt, Ark Anglers) and in the later spring and early summer becomes very active and consequently drifting more just before it pupates. During the 3-5 weeks of pupation, the Hydropsychidae larva, glued to bottom, is almost inaccessible to trout. However, because the upper Arkansas River has hosts some 50 caddis species, the warmer months of the season almost always have a caddis species becoming more active pre-pupation. So, starting in early April, I often search for trout action with the Gilly caddis larva imitation in the mix of flies tried. Check your local hatch chart for when the targeted caddis hatch--the no-availability pupation time is usually 3-5 weeks before that-- and the active period somewhat even earlier than pupation. Given that 50 species of caddis have been identified from the Upper Arkansas, it pays to give a caddis larva fly a try during the warmer months what ever river you are fishing. Probably a good technique on any caddis-bearing river.