Page:Popular Science Monthly Volume 53.djvu/677

Rh a portion of the remarkable silk-spinning family of the Bombycidcæ, but offer many points distinct in themselves, which entitle them to rank, as recent lepidopterists agree, as a separate and well-defined tribe.

Their geographical distribution is extensive, since they are found in Europe, in North and South America, the West Indies and Mexico, in northern India and Ceylon, in China, the South Sea Isles, and Australia, being most abundant in subtropical regions. Wonderfully few species are described as natives of the United States, while in California, unfortunately, three have been discovered solely in the larval state, the more mature conditions of the species as yet eluding detection. But there, as in various other parts of the globe, probably greater numbers await the industry of observers.

Among English-speaking folk, the common appellations for the moths originate in the same circumstance as the popular term in Germany—house-builders, sack-bearers, basket-carriers, basket-worms, case moths; by these names they pass in England, America, and Australia, on account of the singular habitations or sacks they weave for the well-being of the caterpillars in the early stages of their growth. Through the whole of their larval life they carry the protecting structure about with them; and as regards the apterous female, she never leaves this home in which she dwelt while in larva—one of the oddest incidents in this odd economy—but reaching maturity, and bringing forth her young, dies at last, without once quitting her self-constructed prison. She deposits her ova, an immense number, within the body of the case, closely enveloped in some species in a short silky down, and almost as soon as hatched the larvæ force their way out of the puparium which had served for the defense of the eggs, deserting their early abode, and going into the world to follow independent lives. Escaping in crowds from the lower end of the tube, to some twig or leaf, they immediately commence to prepare for themselves each a separate case, arranged in every respect as the larger ones, even before they have taken food.

Particles of wood or bark, leaves, sticks, straws, lichens, mosses, and other vegetable substances form, among the different species, the outer covering or decorative fortification of the house; the interior is lined with soft silk, and interwoven silky threads likewise bind together the external fragments. In the building materials chosen, and their arrangement, Metura elongata is a most interesting architect. Strengthening the large elongate ovate bag of silk, and worked into it, irregularly, numerous rows of short sticks appear, rather distantly separated, and about half an inch long, generally speaking, but toward the lower end there are usually several