Arkansas River Rendezvous

Brown trout caught during the caddis fly hatch

When the weather cooperates as in warm sunny days, anglers can expect great dry fly action for the Arkansas's good population of brown trout.

By Dennis McKinney
Outdoors Journal
Colorado Division of Wildlife 

When the swallows come back to Cotopaxi and their summer homes among the cliffs of the Arkansas River Canyon, their arrival conveniently coincides with the famous Mother’s Day caddis fly hatch on the Arkansas River. The hatch is a time of plenty for the cliff swallows, as swarms of caddis periodically fill the air above the Arkansas River. Arriving when an abundance of food is waiting at the end of their long migration from South America suggests clever scheduling by the swallows.

However, the simultaneous appearance of the birds and the bugs in the canyon in mid-April could be purely coincidental. Cliff swallows, after all, are punctual by nature. The birds are well known for showing up somewhere on a predictable date each spring. The most famous being the swallows that fly back to the San Juan Capistrano Mission in southern California, always arriving within a day or two of March 19.  

Fly-fishing pilgrims also show up for the rendezvous, but their appearance is not coincidental. Their arrival corresponds entirely with the caddis hatch and the fabled trout fishing that follows. The anglers hardly notice the swallows, even as the birds perform amazing acrobatics over the river, gliding and diving as they snatch the caddis in mid-air and pluck them from the river’s surface. Instead, the anglers are focused on feeding frenzies occurring below the surface, as brown and rainbow trout queue up to feast on the emerging insects.

After a year of lumbering around on the riverbed in a cumbersome case, caddis larvae undergo a remarkable change. As the water warms, they retreat inside their cases, sealing the opening behind them. Inside the cocoon, the worm-like larvae transform into adult-like pupae. During hatching periods, great numbers of pupae crawl out of their cases for a wild ride to the surface. When free of the case, the pupae drift along the bottom while gasses build rapidly inside the pupal husk, which shoots them toward the surface like a cork. At the surface, the pupal husk splits open and a fully developed adult insect pops into the air. Swallows, trout, and anglers treasure the individual phases of the caddis hatch.  

When the river is charged with emerging caddis, trout, including larger brown trout, often feed on the insects near the surface. Scores of anglers make the pilgrimage to the Arkansas River at this time for what they consider the first major dry-fishing opportunity of the year. However, by waiting for the caddis, anglers have been missing the less famous but no-less fantastic blue-winged olive mayfly hatches, which have been bringing trout to the surface for several weeks.  

Once underway, the caddis hatch progresses slowly up the Arkansas River from Canon City to Salida, Buena Vista, and beyond until shut down by runoff. The hatch is unpredictable on a day-to-day basis, sometimes erupting several miles upriver of the leading edge and then falling back. The hatch usually reaches Salida around the middle of May.

Caddis hatch tactics:

During times of peak activity, anglers sometimes can pinpoint the heaviest part of the hatch by driving Highway 50 alongside the river and watching for caddis flies hitting the windshield. However, guides and experts at local fly shops agree that the best fishing is not in the midst of a blizzard hatch. They advise taking a position upriver or downriver of the heaviest activity, where fewer caddis are hatching, the trout are feeding, and your artificial fly is not lost in a blizzard of live insects.  

Fishing the hatch is an exercise conducted from the bottom up. Begin by drifting a weighted caddis pupa imitation along the bottom for a short distance and then stopping the rod midway through the drift, which causes the fly to swing toward the surface. This technique imitates the pupae as they crawl out of the case and drift near the bottom while building the gasses that float them to the surface.  

Strikes may occur at any time during the bottom drift or on the swing. The use of a strike indicator will increase the number of hook-ups while the fly is drifting, but many strikes are missed on the swing because the line is tight, and trout have trouble sucking the fly into their mouth. Holding the fly line loosely and letting it slip when a fish strikes will increase hook-ups.  

Another effective tactic employs fishing with a dry/dropper tandem fly rig, which consists of a dry fly such as an Elk-hair Caddis riding on the surface and a weighted pupa imitation trailing below. Again, most strikes will come toward the end of the drift as the pupa reaches the surface.  

Although trout may appear to be taking adult caddis at the surface, they are more often taking the pupae in the surface film. When taking the adults, trout make a splashy rise as they try to capture the insect before it flies away. When taking the pupae, the rise is more subtle, with just the back of the fish breaking the surface.  

Perhaps the best opportunity for dry-fly fishing occurs after the main hatch has passed. After breeding, female caddis return to the river, dipping repeatedly to the surface as they deposit their eggs. Dry flies fished downstream and skittered across riffles or flitted up and down on the surface are proven techniques.