An interesting fact about the movable case made by the clothes moth caterpillar is that the nearest thing in nature to it is the case made by the aquatic grubs or caterpillars of another kind of insects—the caddis-worms (“case-worms”) which are common in ponds and streams. They show extraordinary powers in making their cases so that they balance nicely in the water, as the animal crawls along on the bottom of a pool, with his head and six legs emerging from one end of the case. Caddis-worms are of various kinds or species, and some attach to their cases little broken sticks, others minute empty snail-shells, others the fine green threads of water-plants. The caddis-worm becomes changed into a delicate fly, with transparent wings, just as the clothes-grub becomes changed into a moth—and it is an interesting fact that the caddis-flies, though they are classed with the May-flies and such net-winged insects, and not with the moths and butterflies (the _Lepidoptera_, or insects with wings covered with dust-like scales, which give the colour and patterns to the wings), yet agree with moths in having some scales on the wings and with one kind of minute moth, namely, the clothes moth, in having grubs which make movable cases. The clothes moth caterpillar was known to the Romans by the name _Tinea_, and is described with correct detail by the Roman naturalist Pliny. Modern naturalists have accepted this name _Tinea_ as that of the genus to which the clothes moth belongs. There are thirty different British species of _Tinea_, of which four are guilty of attacking animal fabric, and so causing trouble to man. The one which builds a case and is the titular chief of the clan of clothes moths—“the” clothes moth, just as one may say “the” Macintosh—is scientifically indicated by the name _Tinea pellionella_. The other three do not form movable cases when in the caterpillar stage, and attack coarser stuff than fur and fine wool. One of them is known as the “tapestry moth,” because its caterpillar establishes itself in old tapestry and carpets, and burrowing into these thickish materials is concealed without the aid of any self-provided tunic or case. The name _Tinea_ is often used by entomologists in an expanded form as _Tineina_, to indicate the whole series of minute moths of which the genus _Tinea_ is only one little group. Many of these moths are much smaller even than the clothes moth, and they are found in all parts of the world and in all sorts and conditions of life—in relation to trees, shrubs, and plants of all kinds. It has been estimated that there are as many as 200,000 distinctly marked different kinds of these minute creatures. The insect collectors and students who occupy themselves with the magnificent butterflies and larger moths (of which there are an enormous variety of kinds) refuse to deal with the somewhat dull-looking and almost innumerable minute moths which are classed as _Micro-lepidoptera_, in