Fountains of Youth – Classic trout flies that have withstood the test of time … flies that remain “forever young”

by Rusty Dunn

Stoneflies are named as such for the stony-bottomed, well-oxygenated streams that the insects prefer. May­flies for the month of May, which is when hatches of his­tori­cally important English species reach their peak. What about caddisflies? How were they named? To­day’s term ‘caddis’ originated in the middle ages from the root word ‘cod’, which is a husk, bag, or pouch enclosing vari­ous contents. Larvae of many cad­disfly species live within such cods, which are known today as ‘cases’. Dame Juliana Berners recommended use of cased cad­dis larvae as live bait (“put on thyn hoke a cod­worme”) in her 1496 manuscript A Treatyse of Fishing with an Angle. ‘Cod’ and ‘cad’ were often used inter­changeably in Middle English, and by the 1600s, common names for cased cad­dis were various permutations of both words, in­cluding ‘cad bait’ (1620, Secrets of An­gling), ‘cados worme’ (1634, Theatrum Insectorum), ‘Cadis-worme’ (The Com­pleat Gentle­man, 1622), and ‘cadice’ (The Art of An­gling, 1651). The modern spelling ‘cad­dis’ ap­peared as early as 1653 in the first edition of The Compleat Angler by Isaac Walton, whose entomologi­cal naiveté was evi­dent when he wrote that a trout “especially loves the May­flie, which is bred of the Cod-worm or Caddis”.

Caddisflies inhabit all trout water and are espe­cially important in streams with compromised water quality. As water quality declines, the num­ber of aquatic in­sects declines similarly. Stoneflies are the first to dwindle in number, followed by mayflies. As the food base of such streams shrink, so does the sustainable popu­lation of trout. The good news is that cad­disflies are a hardy lot, per­sist­ing in the face of most human insults. You’ll find vary­ing num­bers of stone­flies and mayflies during your trouty trav­els, but caddisflies will al­ways be there. A well-stocked box of cad­disfly imitations is per­haps your most dependable angling com­panion.

Most caddisfly species build cases of sand, gravel, or vegetation glued together with a sticky secreted silk. Caddis larvae live within such protective cases, which are attached to rocks or wood on the stream bottom. Many caddisfly species carry their cases like travel trailers as they forage and move about the bot­tom. Trout feed on cased caddis by pluck­ing them from rocks or tak­ing the cases as they drift in the current. A few cased cad­dis probably drift throughout the day, but greater num­bers are available during times of ‘behav­ioral drift’. Like many aquatic insects, cased caddis exhibit a daily behav­ioral drift during which oc­cupied cases de­tach from the bottom at re­produci­ble times and drift downstream be­fore reattach­ing. Behav­ioral drifts of most aquatic in­sects peak at dawn and dusk, but those of several im­portant cad­dis species occur in midday. Trout readily feed on drifting cases, es­pe­cially when little else is hatching.

Many generic nymphs are reasonably good imitations of cased caddis, but the Strawman nymph, designed by Detroit’s Paul Young, was the first to explicitly imitate the group. Paul Young is most famous for his delight­ful hand-made split-bam­boo fly rods, but he designed and offered for sale “Straw­man Nymphs” in his tackle catalog as early as 1927. The pattern was later published in Young’s 1934 book Making and Using the Dry Fly.

Today’s most popular cased caddis imitation is probably that of George Anderson, owner of the well-known Living­ston MT fly shop “George Anderson’s Yellowstone Angler”. He designed the Peeking Cad­dis in the 1970s to imitate the Mother’s Day cad­dis hatch of the Yellowstone River. Quoting Ander­son, “The key to tying an effective (cased caddis) imi­tation lies not only in imitating the case but in convinc­ing the trout that it actually con­tains life”. His pattern imitates a cad­dis larva protrud­ing from the open end of its chim­ney-like case. A band of brightly col­ored dubbing imi­tates the abdomen, and a collar of ostrich herl imi­tates the thorax and head. The fly works well wher­ever trout are found. If you’ve ever been puzzled by the seemingly inexplicable effectiveness of John Bethke’s Pink Squir­rel, look no further than George An­der­son’s Peek­ing Caddis for guid­ance.

Copyright 2026, Rusty Dunn

Peeking Caddis

Cream and bright green are the most frequent body colors of chimney-cased caddis larvae.