As a youngster, my grandparents introduced me to fly fishing on Salmon Kill Creek in northwestern Connecticut. Since memories began, I recall the bamboo fly rods sitting on their pegs outside the fishing shack with the silk lines stripped out and drying in the sun between outings to the creek.
When preparing to go out on the water, the lines were re-coated with Mucilin and “cat gut” leaders were tied on. When I suspiciously asked if the leaders really were made from cat guts, my grandfather only smiled, but in a manner that suggested I could chew on one to find out.
Turns out that “cat” was short for “caterpillar,” but guts were involved.
Whitney Tilt, Editor
Adult domestic silk moth (Bombyx mori), photo courtesy of Nikita, Flickr.
Fishing with Guts, by Paul Schullery, Midcurrent
IN THE EARLY 1700s, after anglers had been using horsehair lines for more than a thousand years, they finally discovered that nature had a better idea. It was a natural leader material that, by comparison with horsehair, was so remarkable for translucence, flexibility, and strength that it would eventually dominate the sport. It was silkworm gut. Gut was the raw material from which the larvae of Bombyx mori, a species of Asian moth, spun silk. When this larva ( commonly called the silkworm) reached the growth stage at which it would start spinning its cocoon, it contained two long, thin sacs or “envelopes” running longitudinally nearly the length of its body. Each sac held a tightly bundled mass that when unwound, stretched, and properly treated would make a single strand about twelve to fifteen inches in length — just right for a tippet, or, if several were knotted together, a whole leader.
Adult moth with eggs (left); larva (center), which contained two gut sacs (right)