I consider myself blessed to live in Colorado where we have the opportunity to fish year-round. The Centennial State is known for its world-class tailwaters that support a rich and diversified aquatic life, as well as, impressive populations of trout. If you’re a die-hard angler, and willing to battle the elements, you’ll find a few cooperative trout on just about any winter outing.

Success during the winter begins by familiarizing yourself with a midge’s lifecycle. Weed-rich tailwaters typically produce 3-5 broods of midges per calendar year, which means tailwater junkies have to imitate the various stages of their development (larvae, pupae, and adults) on a non-stop basis.

Larvae look like little segmented tubes and are uniform throughout their wormlike bodies. A healthy trout stream has hundreds of midge larvae per square meter living in the substrate. They are an important food source for opportunistic trout because they frequently become victims of catastrophic drift. I recommend carrying plenty of pale-olive and red larvae (blood worms or blood midges) in your arsenal of flies. I typically dredge my larvae imitations with a lot of weight, fishing them near the streambed, where their largest concentrations are found.

The intermediate stage of a midge’s lifecycle is referred to as the pupae. Pupae have a robust thorax, which contains the wings and legs of the emerging adult. To match the hatch—use the size, shape, and color formula, a foolproof method of choosing the appropriate fly. Pupae tend to be shades of brown and black with distinct segmentation. As the hatch intensifies, I recommend clipping off your larvae and replacing them with pupae. Pupae imitations should be fished mid-column, which requires anglers to constantly adjust their weight and strike indicator to achieve the proper depth. Too much weight is as problematic as not enough.

Once you see adults on the water, look to see if the fish are eating them. If you see trout eating both pupae and adults, use a dry and dropper to imitate both stages of development until they switch to keying on the adults. Once they commit to the adults, snip off your dropper and fish with one or two dry flies.

These are some of my favorite midge imitations. I hope you find them as productive as I have over the years.

Pale Olive Midge Larva

Hook: #16-20 Tiemco 2487
Thread: Light Cahill 8/0 Uni-Thread
Underbody: Light Cahill 8/0 Uni-Thread
Body: Clear Micro Tubing
Head: Light Cahill 8/0 Uni-Thread

Notes: Proof that less is more when it comes to imitating midge larvae. Don’t let the simplicity of this pattern fool you; it’s one of my top producing guide-flies.

Mercury Blood Midge

Hook: #18-22 Tiemco 200 R
Bead: Clear silver-lined glass bead (extra small)
Thread: Red 8/0 Uni-Thread
Rib: Gold Ultra Wire (extra small)
Abdomen: Red 8/0 Uni-Thread
Thorax: Peacock herl

Notes: One of my favorite attractors in a tandem nymphing rig. I typically drop one or two pupae off this pattern. This is a great substitution for an egg pattern during the shoulder seasons when hordes of anglers are using them. Some of my biggest trout of the season are fooled with a Mercury Blood Midge.

Top Secret Midge

Hook: #18-26 Tiemco 2488
Thread: Dark brown 8/0 Uni-Thread
Rib: White 6/O Uni-Thread
Wing: Glamour Madeira
Thorax: Rust brown Superfine dubbing

Notes: This is my go-to small fly during the winter months. It is tied on a Tiemco 2488, which is a 3X wide, 2 X short hook, allowing for an excellent hook-up to landing ratio on even the smallest of offerings. Oftentimes, the difference between catching a few fish and not catching fish at all, is fishing with a size 24 or 26 instead of a 22.

Mercury Flashback Black Beauty

Hook: #18-24 Tiemco 2488
Bead: Clear silver-lined glass bead (extra small)
Thread: Black 8/0 Uni-Thread
Flashback: Pearl Mylar Tinsel (small)
Rib: Copper Ultra Wire (extra small)
Abdomen: Black 8/0 Uni-Thread
Collar: Black Superfine dubbing

Notes: One of my favorite midge pupae that imitates the gas bubble affect during the height of emergence. The highly reflective area in the thorax becomes a trigger to selective trout because of the realistic life-like appearance during emergence. I find flies with a “dash of flash” typically out perform those without any reflective properties.

Manhattan Midge

Hook: #18-24 Tiemco 2488
Bead: Clear silver-lined glass bead (extra small)
Thread: Black 8/0 Uni-Thread
Rib: Copper Ultra Wire (extra small)
Wing: Wing: Glamour Madeira
Collar: Peacock herl

Notes: This pattern was invented by my son Forrest Dorsey. The Manhattan Midge combines the best attributes of the Mercury Blood Midge, Mercury Black Beauty, and Top Secret Midge into one pattern that has fooled selective trout all over the country. In addition to black, try tying it red, and purple.

Matt’s Midge

Hook: #18-26 Tiemco 101
Thread: Black 8/0 Uni-Thread
Abdomen: Black Tying Thread
Wing: White McFlylon or Z-lon
Hackle: Grizzly rooster

Notes: Every tailwater angler should carry a Matt’s Midge in their arsenal of flies. It imitates a newly hatch midge that is trying to escape the waters’ surface and take flight. This is one of the deadliest midge-adult patterns I have ever fished. I typically fish it as a single fly with 6 or 7X tippet.

Hi-Vis Griffith Gnat

Hook: #18-26 Tiemco 101
Thread: Black 8/0 Uni-Thread
Abdomen: Peacock herl
Post: Cerise McFlylon
Hackle: Grizzly rooster

Notes: When you see midge clusters, look no further than Hi-Vis Griffith Gnat when it comes to fooling selective trout that are feeding on clumps of mating midges. This pattern is easy to see in foam lines and hi-glare situations and also doubles for a “locator fly” if you opt to trail something extremely small behind it.

I hope you find some of these tips helpful. Try tying or purchasing some of these flies—I think you’ll be pleased with the results!

Article from Pat Dorsey, a legendary fly fishing guide, professional fly designer and tyer, and an absolute tailwater junkie. For more fishy content full of great looking fly boxes be sure to check him out on Instagram at @patdorseyflyfishing.

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