HOW TO KNOW THE BUTTERFLIES 



follows : In the case of a variable species that is 

 unprotected by any disagreeable quality, any 

 variation toward a protected species will tend to 

 preserve the life of the individual possessing it. 

 And in turn such offspring of these individuals as 

 still more nearly resemble the protected species 

 will be most likely to be preserved. The con- 

 tinued action of this natural selection will result 

 in producing a species that closely resembles the 

 protected one, even though it may be very dif- 

 ferent structurally from the one that it mimics. 



Many instances of unconscious mimicry of this 

 kind are known. They are especially abundant 

 in the tropics where the foul-smelling heliconians 

 are most abundant. The bad odor of these but- 

 terflies when living is so marked that it can be 

 detected by the human nose ; and it is found that 

 many species of them are mimicked by other 

 butterflies, and especially those of the Pieridae. 

 The mimicry is not confined to similarity in 

 coloring, but extends to the shape of the wings 

 and manner of flight. 



The larva of the viceroy feeds upon willow, 

 poplar, balm of gilead, aspen, and cottonwood. 

 The species is two- or three-brooded, and hiber- 

 nates as a partially grown larva in a nest made of 

 a rolled leaf. This nest is lined with silk, and the 



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