The Roman consuls

Arthur Thomas FisherRod and River: Or, Fly-fishing for Salmon, Trout and Grayling, Londres, Richard Bentley, 1892, p. 106-109.

In proces of time the eggs are hatched, and the young larvae then proceed to construct houses in which they can dwell. These houses are formed of various materials, and are of various shapes, and, indeed, not only does each species have its own particular form of house, but there is considerable variety even in the house of a single species… The materials of which the nest is made depend greatly on the locality in which the insect is hatched, and in a rather large serie of caddis nests now before me there are some very remarkable instances of the manner in which the insect has been obliged to adapt itself to circumstances. The most common style of case is that which is composed of a number of sticks and grass-stems laid longitudinally upon each other, like the fasces of the Roman consuls. Of these I have specimens of various sizes and shapes, some being barely half an inch long, while others measure four times that length, the sticks being placed sometimes so irregularly thet the home of the architect is not easily seen. The creatures are not all particular about the straightness of the sticks, but take them of any degrees of curvature… Another case is made of the hollow stems of some plant, apparently that of a hemlock, to which are attached a few slips of bark from the plants. Next comes a series of cases in which the caddis larva has contrived to secure a great number of cylindrical grass-stems, and arranged them transversely into several sets, making one set cross the other so as to leave a central space in which the litttle architect can live.

One or two cases are made wholly of bark, apparently the cuticle of the common reed, a plant which is very common reed, a plant which is very common in the Cherwell, whence the cases were taken. In all probability these strips of cuticle have been dropped into the river by the water-rats while feeding on the reeds.

Several cases are made entirely of leaves, mostly taken from the whitethorn, which grows in great quantities along thebanks of the above-mentioned river. Then there are cases which are entirely composed of sticks and leaves, these materials generally occupying opposite ends of the case. There is another series of cases made up of fine grass apparently the débris of hay which has been blown into the water during the summer, and having the materials laid across each other like the needles of a stocking-knitter. Most of these cases are balanced by a stone.

Next come a number of cases which are composed of small shells, those of the Planorbis being the most common, and having them a few specimens of the Limnaea, or pond-snail, and many sperate valves and perfect shells of the fresh-water mussel. The caddis larva is an incorrigible kidnapper, seizing on any shell that may suit its purpose, without troubling itself about the inhabitant. It is quite a common occurrence to find four or five living specimens of the PLanorbis and Limnaea affixed to the case of a caddis larva, and to see the inhabitants adhering to the plants and endeavouring to proceed in one direction, while the caddis is trying to walk in another, thus recalling the well-known episode of the Tartar and his captor. In these cases the cylindrical body is made of sand and small fragments of shells bound together with a waterproof cement, and the shells are attached by their flat sides to the exterior.

There are severall cases which are made entirely of sand cemented together, some being cylindrical, and others tapering to a point, like an elephant’s tusk. There are also examples of mixed structures, where the caddis has combined shells with the leaf and twig case, and in one of these instances the little architect has bent back the valves of a small mussel, and fastened them back to back on its house. Beside these, there are one or two very eccentric forms, where the caddis has chosen some objects which are not often seen in such a position. The seed-vessels of the elm are tolerably common ; but I have several specimens where the caddis has taken the operculum of a dead pond-snail, and fastened it to the case ; and there is an example where the chrysalis of some moth, apparently belonging to the genus Porthesia, has been blown into the water from a tree over-hanging the stream, and seized upon by a caddis as a unique ornament for its house. These latter examples were found in a stream in Wiltshire, and the tusk-like sand-cases were found in a disused stone-quarry in the same county.

Various experiments have been tried upon the larva of the caddis in order to see its mode of building. A lady, Miss Smee, has been very successful in this pursuit, and has forced the caddis larvae to build their nests of the most extraordinary substances, such as gold-dust, crushed glass, and other substances. They would not however, use beads, or anything where the surface was smooth and polished.
In this remarkable sub-aquatic home the caddis larva lives in tolerable security for  the head and front of the body are clothed in horny mail, and the soft white abdomen is protected by the case.