By Dave Ruetz
Of the most common insect orders (mayflies, stoneflies, caddisflies) found in trout streams, caddisflies seem to be the most difficult to figure out.
Much has been written about caddisflies recently, but few fly fishers can recognize whether trout are feeding on emerging or egg-laying caddisflies and as a result they are confused about fly selection and strategies.
CADDISFLY EMERGENCES
Like mayflies, most caddisflies rise from the bottom of the stream and emerge in the surface film. Unlike the slower mayfly, however, once a caddisfly breaks out of its pupal husk in the surface film and becomes a winged adult, its movement from the stream to dry land is relatively fast. Mayflies generally float on the surface of the water, often for a considerable distance, while their wings dry and stiffen.
Because it is uncommon for caddis adults to stay long on the water, a pattern imitating the emerging pupa fished in or just under the surface film is preferred by the trout.
To confirm an emergence of caddisflies, watch the fish and how they feed. The splashy riseforms and aggressive feeding of trout are signs of caddis activity, but there are other indicators. Riseforms are a result of many factors: the type of water a fish is holding in, the size of the fishand the behavior of the insects being fed upon. Many species of caddisflies emerge from fast water, and, generally, the faster the water, the more energetic the riseform as the fish reacts to escaping insects.
However, even in a fast-water scenario, anglers can be fooled. Look closely, often trout will feed in a thin seam just off the fast water, eating pupae that have been caught there. In fact, observation is crucial whenever you are in the midst of a caddisfly emergence.
Typically, in the early stages of a caddis emergence, the riseforms of the trout are splashy and aggressive, even in slow water. These riseforms are often caused by smaller fish. As emergence becomes more intense, the fish frequently settle into a consistent, less frantic feeding rhythm. Look for porpoising fish: first the head of the trout will appear at the surface, followed by the back, then the tail. When fish are porpoising and there are few adult flies on the surface, the pupae most likely are concentrated in or just under the surface film. At these times, a pupa pattern, such as the LaFontaine Sparkle Emergent Pupa, is deadly when fished in the surface film.
To confirm whether the trout are actually feeding on caddis pupae, hold a fine mesh net, such as an aquarium net, in the surface film downstream of feeding fish for several minutes. Look for fresh caddis pupal husks. They will appear transparent, with a slight yellow-orange tint, and should provide clues to determining the size and shape of the emerging species.
The most effective way to fish pupal patterns during caddis emergences is to dead-drift them in the surface film, as you would fish a dry fly. Grease the leader and tippet to within six inches of the fly to help suspend it in the surface film. If the pupa pattern