176 ELEMENTARY ZOOLOGY 



have hibernated in the adult condition. From the eggs 

 the minute, cylindrical, pale-green, black-headed larvae 

 hatch in four or five days. As soon as hatched the 

 larva devours the eggshell from which it has escaped and 

 then feeds voraciously on the milkweed leaves. It grows 

 'rapidly, and in three or four days a blackish band or ring 

 appears on each segment, and for the rest of its life it is 

 very conspicuously colored with its black rings on a 

 yellowish-green background. It molts three times, and 

 in from twelve to twenty days is ready to pupate, or 

 change to a chrysalis. 



When ready to pupate the larva usually leaves the 

 milkweed plant, and seeks some such protected place as 

 the under side of a fence-rail or jutting rock. Here it 

 attaches its posterior extremity by a small silken web to 

 the rail or rock, and casting its larval skin appears as a 

 beautiful pale-green chrysalis with ivory black and golden 

 spots. It hangs motionless, and of course without taking 

 food, for from a week to two weeks (according to 

 season and temperature), when the pupal cuticle breaks 

 and the great red-brown butterfly (fig. 165) issues. 



The butterfly feeds fas is indicated by the structure of 

 its mouth-parts) very differently from the larva; it sucks 

 up by means of its long tubular proboscis the nectar of 

 flowers, nor does it confine itself at all to the flowers of 

 milkweeds. It is a fine flyer and a great traveller. Many 

 thousands of these butterflies often make long flights or 

 migrations together. At other times tens of thousands 

 of these butterflies congregate in a certain limited area, 

 clinging sometimes to the branches of a few trees in such 

 numbers and so closely together as to give the tree a 

 brown color. Such a " sembling " of monarch butterflies 

 occurs every year near the Point Pinos lighthouse on 

 the Bay of Monterey, California. The object of this 

 assembling together is not understood. Both the larvae 

 and adults of the monarch butterfly are distasteful to birds, 



