Anonyme, « Instinctive Knowledge of Insects », Monthly Literary Miscelian A Compendium of Literary Philosophical and Religious Knowledge, Quinby, Wood & Russell, 1852, p. 503-504.
The caddis worms, or larvae of the fourwinged flies, in the order Trichoptera, live under water, where they construct for themselves movable habitations of various materials, according to their babits or to the substances most conveniently procured, such as sand, stones, shells, wod and leaves. One of these grubs forms a case of leaves glued together longitudinally, but leaving an aperture sufficiently large for the inhabitant to put out its head and shoulders when on the look-out for food ; another employs pieces of reed-grass, straw or wood, carefully joined and cemented together ; another makes choice of the tiny shells of y oung fresh-water naussels and snails to form a movable grotto , and as these little shells are for the most part inhabited, he keeps the poor animals close prisonnes, and drags them along with him. But one of the most surprising instances of their skill occurs in the structures of which small stones are the prinvipal materials. The problem is to make a tube about the width of the hollow of a wheat-straw, and equally smooth and uniform ; and as the materials are small stones, full of angles and irregularities, the difficulty of performing this problem will appear to be considerable, if not insurmountable ; yet the little architects, by patiently examining their stones, and turning them round on every side, never fail to accomplish their plans- This, however, is only part of the problem, which is complicated with another condition, namely, that the under surface shall be flat and smoth, without any projecting angles which might impede its progress when dragged along the bottom of the rivulet where it resides. In some instances, where these little cases are found to possess too great a specific gravity, a bit of light wood or a hollow straw is added to buoy them up.