The Cache la Poudre flies patterns are similar to the ones used on the Big Thompson and the St Vrain. With it being a larger river if you can throw some bigger patterns they will be easier to see. The river mostly freezes over in the winter so we will only talk about summer patterns. This is also a good river to throw streamers or some articulated patterns.
Both St Peters and Anglers Roost have some excellent patterns and a large selection of flies.
1. Chew Toy Stimulator #8 - 16
This fly is a regular simulator with rubber legs and a foam wing. This helps the fly float longer and you will have to apply less shake and bake to keep it riding high. This is also a good fly to hang a dropper off of for a two fly rig. This is a St. Peters fly.
2. Woolly Bugger #8 - 10
This is a standard for
trout and you can fish it dead drift or with a little action. Always a
good pattern to have lots of not just used as a Cache La Poudre flies.
3. Goddard Caddis #12 - 16
This pattern is like an Elk Hair caddis but has a clipped Dear hair body. The most distinguishing part of this fly is the two long antenna. Remember you can fish your caddis patterns with a little life and I have great luck bouncing this pattern off the surface with a short line. Another good way is to dead drift it down stream and then strip it in.
4. Guides Choice Hare's ear # 14 - 18
This is a good fly to use in a dropper combo during the summer months. The Chew Toy floats high and you can use it like a bobber. This way you are giving the trout two options and they are just as likely to hit the dry as the dropper.
5. Zebra Midge #18 - 22
If I am not having any luck on other nymph patterns, it seems like the midge always produces. The midge is the most common food source for trout and they are used to seeing them all the time. Fish this pattern deep with a strike indicator and make sure it has enough time to get down. If you want to tie flies this would be a good pattern to work on. You will lose a lot and it is easy to tie with a thread body and copper for the ribbing.
Check back often as I will add more Cache La Poudre flies as I hear about them.