Anonyme, « Larvae of the Caddis Fly form an important food of many fishes »Outdoor Indiana, Indianapolis, Indiana Department of Natural Resources, vol. 5 n°1, 1938, p. 4 et 25.
Larvae of the Caddis Fly form an important food of many fishes
Often Confused with the Hellgrammite-Builds Own Home from Leaves, Grass ans Stones to Resemble Small Tube.
No, Brother, the hellgrammite of the winter is not a hellgrammite no matter what it has been called. Science says so, and adds that the thing called a hellgrammite is really a caddis fly larva. Also, the caddis fly is a carpenter, jeweler, mason and tailor, and silk thread is used this accomplished animal, Silk is so favored by this fly that, no matter what kind of house he builds, he always has a silken couch. Sometimes the name is spelled caddice and sometimes caddis. When you see a caddis fly on land it often is called a moth, though it is not a moth. Sometimes it comes to light by the thousands and becomes a nuisance, but it is a good fish food and is one of the kinds of life that feed the fishes naturally in the stream. In winter it is a favorite bait of the winter fisherman, who calls the larva a hellgrammite, though the true hellgrammite is a much different and larger animal.
The caddis fly lays its eggs in the water or on vegetation just above the water. The eggs usually are glued into a mass, and when the water touches this glue, it expands into a sort of Jelly.
The eggs hatch into larva, worms or « hellgrammite », and these caddis worms are the mechanics. In this picture that accompanies this article you will see a caddis worm and its home. The home is a case and caddice or caddis means case. Some of these cases are made of dead leaves, some of stems of grass, some are built of stones, set as carefully into the case as if a jeweler had done the job. The one in the picture was a kind you find in northern indiana in winter, in sluggish streams.
The case in this pictures is made of three pieces of hollow stem. These pieces have been carefully tailored together to fomr a rather long tube and the larva gets Inside this tube and spins a silk couch. It then lies Inside the silk couch and Inside the stem, and sticks its head and front legs outside when it wishes to crawl around to find its dinner.
A poor fish, out looking for its own dinner, might think the case merely a piece of rotting vegetation, but when the larva sticks its head out and starts to crawl around, a fish might gobble it up. The contents of the stomach of a fish might jeave the idea that the fish was feeding on dead leaves and stems, but apparently the stems, in such cases would be eaten for the caddis larva and not for its house.
In some species, the caddis worm will gather small straws and make a case that look like an old-fashionned stick and mortar chimmery. The sticks are laid up much like the structure of a log cabin.
Other species may cement small stones together and then stick larger pieces of stone on the outside of these. This structure looks a good deal like a stone chimney.
One of the oddest accomplishments of the larva is to build an imitation of a snail shell. The job is so carefully done that one book of science tells you that one scientist actually described a caddis houses as a new species of snail, and probably got laughed at for his mistake ; but it would be an easy mistake to make. Apparently, this species of caddis like to take its rest curled up as if the weather were rather down in the winter water.