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,@, 4). Through the 
egg is an opening (Fig. 26, B 7), the micropile, 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 
