Early Spring fly fishing in Colorado is excellent and many anglers are already flocking to local rivers near Vail, Colorado searching for big brown and rainbow trout. Well known hatches of Blue-winged Olive mayflies and a variety of midges hatch each day on rivers like the Eagle and Roaring Fork Rivers. These small insects are the first steady food source for trout and smart anglers will have a good supply of flies imitating BWOs and midges in their fly boxes.
An even smarter angler will be aware of the fact that every spring there are other lesser known hatches that often take the forefront with trout that are looking for bigger bugs. Some of these hatches occur predictably every year while others may only show up during the right conditions. Because of the warmer than average winter this year and a very pleasant early spring we are already seeing some hatches that anglers may not be familiar with but need to understand. While midges and BWOs are very important, it is crucial not to have tunnel vision as a fly fisherman and open to pay close attention to what is happening throughout the day, watch for new hatches and be ready to try some new flies. The great thing about these lesser-known hatches is the bugs tend to run much larger than typical spring hatches of BWOs and midges.
Colorado Spring Stoneflies
Salmonflies, golden stoneflies and yellow sallies may be the most well-known of the summer stonefly hatches but every spring on the Colorado River, Eagle River and Roaring Fork River we experience some good stonefly action similar to the famous Skwala stoneflye hatch found in Montana. These spring hatches of Colorado stoneflies tend to run about a size #10-12 and most are either olive or brown in color. For flies it’s hard to beat a big prince nymph or 20-incher while a peacock Stimulator works well on the surface.
Colorado Spring Caddis
The Mother’s Day Caddis hatch is very popular on Colorado’s Arkansas River but also happens each spring on the Roaring Fork and Eagle River. The name “Mother’s Day Hatch” can be a bit of a misnomer since some years the actual caddis hatch starts much earlier. It’s not uncommon to see caddis hatching in big numbers on the Roaring Fork in early April and a week or so later on the Eagle River. Colorado’s spring caddis tend have a dark body ranging from black to olive. Sizes vary from big #12s to smaller #16. The Guide Choice in olive is a great nymph/emerger while a Black Foam Caddis is a fantastic dry fly.
March Browns-The Other Spring Mayfly
Blue-winged olive mayflies are a sure sign of great spring fly fishing in Colorado but they’re not the only mayfly on the menu. On both the Eagle and Roaring Fork, March Browns are present in enough numbers to be a factor on some spring days. On a recent float trip on the Roaring Fork, March Browns were hatching and the fish were definitely paying attention to these larger mayflies. This hatch is certainly not as predictable some other but during warm spring with clear water you may run into them anytime in April or early May. These mayflies run large at around a size #12 with a brownish body sometimes running towards olive or grey. The old reliable flashback pheasant tail or soft-hackle pheasant tail works effectively for nymph and emerger patterns while a Royal Wulff or Parachute Adams should do the trick on the surface.
The next time you hit the river in Colorado this spring have a box of BOWs and midges ready but be aware that the fish rising on the opposite bank may be eating a bigger bug you failed to notice hatching. Keep the spring stoneflies, caddis and mayflies in mind and in your fly boxes. Head to the Vail Valley Anglers fly shop in Edwards to book a guided fly fishing trip or stock up on spring fly patterns for Colorado.
Brody Henderson, Guide and Content Writer