CHAPTER VII. 
A CHAPTER OF LIFE-HISTORIES. 
The Milkweed-butterfly. In speaking of protective 
coloring we have already mentioned the large and 
beautiful butterfly commonly known as the milkweed- 
butterfly. It is known to scientists as the Danais 
archippus or sometimes as the Anosia plexippus. On 
account of its large size, great beauty, and very general 
distribution, it has been much studied and its life-his¬ 
tory is well known. 
The female butterfly deposits her eggs one by one 
on the under side of milkweed-leaves. These eggs 
when examined with 
the microscope are 
seen to be very regu¬ 
larly carved in a beauti¬ 
ful and delicate pattern. 
The shape of the egg is 
shown in Fig. 63. 
In a few days a little 
black-headed caterpil¬ 
lar, perhaps a tenth of 
an inch long, emerges 
from the egg, eats its 
Fig. 63.—Eggs of Milkweed-butterfly. 
a, single egg, magnified; c, eggs on 
leaf, one half natural size. After 
Riley. 
empty shell for breakfast, and dines upon the milk¬ 
weed-leaf, on which it continues to feed for several 
weeks. At the end of one week, having eaten so much 
and grown so fast that its skin can no longer hold its 
body, it spins a bit of silk upon the leaf, waits until its 
coat splits down the back and then crawls out of the 
68 
