In Colorado, specifically South Western Colorado, Caddis flies are a significant food source for trout. Caddis have the ability to survive and thrive in some pretty poor quality rivers, streams, ponds and lakes. Colorado, with its’ abundance of mines and tailing piles have leached some pretty nasty chemicals into our high country streams over time, and have polluted miles and miles of streams. Whereas Mayflies are like the “canary in the mineshaft” in terms of needing cleaner water to survive and prosper, Caddis are all over the state in an incredible number of waters in the state.
Where the mayfly adult has a classic “sailboat” upright wing, the Caddis Adult has its' own classic, iconic shape, that of a “pup-tent” shaped wing, covered in ultra fine, if not microscopic sized hair. Some wings are rounded on the open end of the “tent”, some are angular. Some wings are solid colors, others mottled or spotted. Wings can be light tan colors on the light end of the spectrum, to dark grey, almost black colors at the other end. Long overhanging antaneae extending forward from their heads and six legs complete the look of this Adult as well as Pupa phases
Caddis, unlike Mayflies exhibit all the metamorphic stages from egg, to larvae, to pupa and to adult. Of course all of these stages have descriptive Latin names attached to them, And while it can be helpful to know these names and phases, for most anglers knowing that caddis can be fished to with patterns that represent the Larva, Pupa and Adult stages will be all they need to know. OK, there is a diving cadis that represents the female egg layer depositing her eggs underwater that can be effective as well!
Caddis fit into one of two main categories—shelter builders or free swimmers. Free swimmers are predators, moving around rocks, in cracks and roaming the stream or lake bottom in search of food. While the shelter builders, or cased Caddis all build some form or house, or case to live in and trap food with. Within the cased caddis group there are five variations of cases. Some are purselike, some build their home of vegetation, some of sticks, some of shells, some of sand or stones. Unlike the three pigs, there are none made of bricks. The case builders are “trappers” for the most part and either seine or build nets to capture food, some even suspend themselves in the currents to be in best place to trap food, via a silken thread.
Like their land based caterpillar counterparts, all Caddis larvae build a cocoon and over the next 2 to 8 weeks, are transformed into the Pupal or “Pharate Adult” stage that then swims up to the. If the Caddis Pupa reaches the surface uneater, it then uses surface tension to hold its Pupal Shuck until it can wriggle out, dry its wings briefly, and fly away. All of these life phases of the caddis are important to the angler. Patterns exist for each stage. And if you think about it will give you hints about how to fish the patterns. The larval stages stay close to the bottom. Deep nymphing techniques with weighted nymphs or weights on the leader to get the pattern down and keep it down excel at this phase. For pupal patterns, since they are in transition from bottom to the surface, you can fish these with heavy weight near the bottom, with less weight in the middle of the water column, "lifted-up" at the end of the drift to imitate their rapid ascent, and then in the film as an emerging insect, vulnerable briefly on the surface as it pops out of its pupal shuck,
briefly dries its wings as the adult. Then the Adult can be fished, “dead drifted” on the surface or “skated” over the surface. The males swarm and the females fly into the swarm for fertilization. She then returns to the water and either lays her eggs on the
surface, or takes in a gulp of air dives underwater at great risk to lay its eggs. Adult Caddis differ from Mayflies in that they still eat food and drink water, and live for days, if not weeks and are available to trout all during that period of their lives. Keep in mind,
that sometimes even during the best Caddis hatches, the Pupa patterns produce the best results. When you look out a thousands of caddis on the water and wonder why a trout would pick yours you will be truly humbled and in awe when you are favored when that occurs. Maybe you’ll be in the right place at the right time and experience a “Caddis blizzard” and the feeding frenzy that cause a town like Salida, Colorado to have a “Caddis Festival”.
While there are almost 12,000 species of Caddis worldwide, and this huge number of species may seem overwhelming, take heart-- the observant angler can narrow fly selection down dramatically by checking hatch charts, check the bushes and vegetation streamside, examine bugs seined from the water, or floating on the surface to see what is hatching. An angler can “cover a lot of ground” with a few patterns to imitate cased caddis, a few cream or green patterns to imitate the free swimmers, a tan, green or dark grey pupa pattern, and various colors and sizes of an “Elk Hair Caddis” in a few body colors and wing colors—light to dark, bodies and wings
Kind of a “Well-Duh”-- In general, imitate what you find in, on and around the water, and match those insects in look or profile, size and color, no matter what its name is.