Maria Charlotte Lees , Summer hours, Ill. de l’auteur, Londres, Darton & Co.,1859, p. 24-27.
BILLY! Billy! What are you doing? He had left our lap and was endeavouring to catch one of those beautiful ephemera commonly known by the name of My-fly. They were singing their way out of sight. Many were the enemies they had to contend with; low-skimming swallow darting over the clear waters in eager pursuit; silver-scaled, red-spotted trout leapt high out of the stream as they rose above them in the sunny air.
“See, mother dear, there is one that has just risen from the water; he has left his empty skin, or case, floating there. Do tell us something about them; they are so beautiful. Tell us where they come from, and how they live?”
“They live, dearest, in a very different shape to what you now see them the longer part of their lives. The Trichoptera, or May-fly, like the butterfly and many other insects, has several changes to go through before it bursts forth the delicate beautiful fly we see it in the summer seasons. Have you never observed, in the drains cut though water meadow’s, or In the shallow streams of which we have so many near us, little oblong moving masses? Perchance you have deemed them merely broken pieces of rubbish moved and swayed by the current. Not so; each of these little masses contained a life, and insect life – a caddis-worm. Pieced of wood, straw, sand, and small pebbles are all collected by this little creature, and glued together so as to form a strong house or case. Within, it is lined with a silk they weave themselves. Others again make the outer covering of leaves rolled like ribbon; but of whatever the outer material, the interior is always soft silk, and its form cylindrical, with an opening at each extremity. Out of one of these, if you consider them with care, you may see a head protruding, with six legs, the hinder part of the body sheltered by the case, which it drags after it like a snail, and like him retreating into it when touched or danger approaches – this little creature not having the power of swimming, but only of crawling on the sand at the bottom of the stream by the aid of its six legs; and the insect itself being heavier than the water, it is of great importance that its case should be of a specific gravity so nearly that of the element it is created to inhabit, that while walking it should be neither incommoded by its weight, or be so buoyant as to prevent its resting on the ground. It is also essential that it should be so equally balanced as to be able to readily to move in any position. Under these circumstances, how wonderful and beautiful is the instinct given to these little animals by the power that forgets none of his minutest and humblest creatures. If the case be too heavy, the caddis-worm will glue to it a bit of straw or a piece of leaf; if too light, a shell or a little pebble. After remaining some time in this form it begins to prepare for the rest, or the torpid stage of its existence. For this purpose, as it would be quite defenceless were its habitation left open at both ends, it weaves for itself strong silken threads, which it fixes like a portcullis at each opening: thus shielding it from intrusion, yet allowing free access to the water, without which it could not exist. When the summer once more comes round, and they are to exchange water for air, Providence provides the means of doing so. On the anterior part of their heads are fixed a pair of hooks resembling in form the beak of a bird, and with these, previously to their last final change, they make an opening in the grating which confines them. The body of the pupa is covered with a thin envelope when it leaves the hard case of the caddis-worm. Each leg, with the exception of the hinder ones, have their distinct cases: stretching out into long antennae, and steering with its legs, it makes for the surface, and bursting its envelope soars up a perfect insect, whose life is to be but that of a few hours’ duration.