Rest H. Metcalf, « Interesting Stones House », Birds and nature magazine, vol. 8-9, Londres, Osprey Company, 1900, p. 55.
While the children were playing in a small brook, they found something entirely new to them, and as usual, came with hands full, shouting, « We have found something new ! Do you know theses are ?Theses news treasures proved to be the larvae of the caddis fly in their stone houses. This little creature is noted for its complete metamorphosis. The female fly often descend to the depth of a foot or more in water to deposit her eggs. As the eggs hatch the habits of their larvae are exceedingly interesting. They are aquatic, being long, softish grubs, with six feet . The fish are very fond of them, for which reason they are in great demand for bait. The angler looks for « cad-bait » along the edges of streams, under stones, or on the stalks of aquatic plants. One can easily see that their lives are not free from care and danger, and so to protect themselves, they are very wise in building cylindrical cases in which they live during this dangerous period. The different species of which there are many, seem to have their individual preference as to the substance which they employ in building these houses, some using bits of wood, others shells, pebbles, or straws. They readily disregard these preferences, when there is a lack of the material which they usually prefer. Those brought to me were made of different colored pebbles and were very pretty homes. We counted the pebbles in one of them and found there were eighty-nine used, and built to securely that it could not be easily crushed by ou fingers. They were all about an inch in length a quarter of an inch diameter and were perfect cylinders with a large pebble fastening one end ; so no fish could catch them unawares. We placed them in water, where we could watch their development. They never willingly left their homes, only thrusting the head and a portion of the body out in search of food.
When about to pass into the torpid pupa state,, they fastened their houses to some sticks and stones in the water, and then closed the end with a strong silken grating, which allowed the water to pass freely through their houses, keeping them sweet and fresh. We are told that this fresh water is necessary for the respiration of the pupa. Thus they remain quiet for a time they are ready to assume the imago form. When that important period arrives they make an opening in the silken grating with a pair of hooked Jaws, which seem to have developed while resting in the pupa state. They also have become efficient swimmers, using their long hind legs to assist them. After enjoying this new exercise of swimming for a short time they …/….
These insects are know as the caddis-fly of the order Neuroptera, having four wings, measuring about an inch when full spread, with branched nervures of which the anterior pair are clothed with hairs ; the posteriors pair are folded in repose. The head is furnished with a pair of large eyes, with three ocelli, and the antennae are generally very long.
If you know the haunts of this interesting house builder, scatter some bright sand and tiny pebbles in the water, and when they are deserted, gather the houses for your collection.