What in all the realm of nature is so worthy to awaken delight and admiration as the astonishing changes which insects undergo? Just think of the sluggish, repulsive caterpillar, dragging its heavy form over clod or bush, or mining in dirt and filth, changed, by the wand of nature's great magician, first into the motionless chrysalis, decked with green and gold, and beautiful as the gem that glitters on the finger of beauty, then bursting forth as the graceful, gorgeous butterfly; which, by its brilliant tints and elegant poise, out-rivals even the birds among the life-jewels of nature, and is made fit to revel in all her decorative wealth. The little fly, too, with wings dyed in rainbow-hues, flitting like, a fairy from leaf to flower, was but yesterday the repulsive maggot, reveling in the veriest filth of decaying nature. The grub to-day drags its slimy shape through the slums of earth, on which it fattens; to-morrow it will glitter as the brilliant setting in the bracelets and ear-drops of the gay and thoughtless belle. There are four separate stages in the development of insects: The egg state, the larva, the pupa, and the imago. THE EGG. This is not unlike the same in higher animals. It has its yolk and its surrounding white or albumen, like the eggs of all mammals, and farther, the delicate shell, which is familiar in the eggs of birds and reptiles. Eggs of insects are often beautiful in form and color, and not infrequently ribbed and fluted as by a master-hand. The form of eggs is very various--spherical, oval, cylindrical, oblong, straight and curved (Fig. 26, _b_). All insects seem to be guided by a wonderful knowledge, or instinct, or intelligence, in the placing of eggs on or near the peculiar food of the larva. Even though in many cases such food is no part of the aliment of the imago insect. The fly has the refined habits of the epicure, from whose cup it daintily sips, yet its eggs are placed in the horse-droppings of stable and pasture.