First Stage of Insects. 77 



gorgeous butterfly; which, by its brilliant tints and elegant 

 poise, outrivals 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, flit- 

 ting 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 bracelet and ear-drops 

 of the gay and thoughtless belle. 



There are four separate stages in the development of 

 insects: The egg, 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 fami- 

 liar in the eggs of birds and reptiles. Eggs of insects are 

 often beautiful in form and color, and not infrequently 

 ribbed and fluted (Fig. 26), as by a master hand. The 

 form of eggs is very various — spherical, oval, cylindrical, 

 oblong, straight, and curved (Fig. 24, a, b). Through the 

 egg is an opening (Fig. 26, B w), the micrbpile, through 

 which passes the sperm cells. 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. 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. 



Inside the egg wonderful changes soon commence, and 

 their consummation is a tiny larva. Somewhat similar 

 changes can be easily and most profitably studied by break- 

 ing and examining a hen's egg each successive day of incu- 

 bation. As with the eggs of our own species and of all 

 higher animals, the egg of insects, or the yolk, the essential 

 part — the white is only food, so to speak — soon segments 

 or divides into a great many cells which soon unite into a 

 membrane, the blastoderm, which is the initial animal; this 

 blastoderm soon forms a single arch or sac, and not a 



