Fly Fishing Abrams Creek

Caddis vs. Mayflies

Literature regarding fly-fishing for trout is so heavily loaded in the direction of mayflies, it is easy for unknowing anglers to overlook the importance of caddis flies. However, in the waters of the smokies, the caddis fly does not take a backseat to the more highly touted mayfly clans in the local food chain. In many ways may and caddis flies are very similar. Each breeds as a winged adult and lays its eggs in water. Upon hatching, the differences in these two aquatic insects are at their most evident.

Mayfly offspring begin life as a nymph, which resides beneath the surface, clinging to rocks and debris located along the bottom, or burrowed in the sand. Usually capable of limited swimming ability, mayfly nymphs live underwater for six to twelve months, and sometimes longer. During that time, they may shed their nymphal outer shell more than one time to accommodate growth. Upon reaching maturity, mayflies emerge to the surface as winged duns. Once airborne, the duns undergo a second metamorphosis, to become breeding adults. Adults return to the streams in great swarms to perform their famous mating dance.Unable to feed because they have no mouth, adult mayflies mate, and they fall spent on the surface of the water, where waiting trout seize these protein-rich morsels thus completing their life cycle.

Caddis flies also begin life as waterborne sub-adult. Rather than being nymphs, though, caddis fly offspring are what biologists refer to as pupa. Whereas a mayfly nymph is a well-armored creature complete with legs and most other visible attributes of an insect, a caddis fly pupa usually looks like a plump, soft little worm resembling a common grub. In His infinite wisdom though, the Creator endowed the caddis fly pupa with all of the tools needed not only to survive in the hostile surroundings of a trout stream, but also to prosper. Caddis fly pupa construct"houses" for themselves that protect them from most predators.

In Park waters some caddis fly houses are constructed of sticks and leaves, while others rely on tiny pebbles and even sand as home-building materials. Sticks, leaves, pebbles, and sand are held together by secretions produced by the caddis fly pupa. One large group of caddis flies in the park constructs net-like seines, which they use to capture their food.

Usually measuring around an inch long, you can find "stickbait," as old-timers refer to the caddis fly pupa, still occupying their abodes, by turning over boulders and picking up the submerged sticks used by these creatures to secure their homes.

Mayflies and caddis flies emerge in a similar manner. Maximum reproduction is facilitated by peak emergences of ready-to-bred adult flies. Sledges, as adult caddis flies are called, rarely ride the surface as long as a mayfly dun. Emerging sledges skitter upstream along the surface in a rapid, erratic fashion. This makes them far more difficult for trout to nab than a stodgy dun who rides along the moving surface waiting for its waxy wings to dry sufficiently for it to become airborne. Many times, peak emergences of caddis flies are difficult to see, while peak emergences of mayflies are often more visible.

Published: 29 Apr 2002 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication


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