ACCORDING TO SEASON 



The Basil- 



archia 



Scent per- 

 ception of 

 butterflies 



Caterpil- 

 lar and 

 chrysalis 



arch butterfly contrived to live long enough to 

 leave descendants; as a consequence, from gen- 

 eration to generation the likeness between the 

 two tribes increased, till at last the Basilarchia so 

 successfully counterfeited the appearance of the 

 milk-weed butterfly that, while still without its 

 weapons of defence, it secured almost the same 

 immunity from its enemies. 



The scent perception of butterflies is astonish- 

 ingly keen. Their vision has been proved to be 

 very imperfect, according to our ideas, and it is 

 believed that they are guided to the plants upon 

 which they wish to lay their eggs, and from which 

 they hope to gather food, by the sense of smell, 

 rather than by that of sight. It is claimed that in 

 certain tribes a female butterfly, emerging from 

 her cocoon quite out of sight and several miles 

 away (in a city, for instance) from any of her tribe 

 is speedily visited by her kinsmen who have been 

 guided hither by the sense of smell alone. 



Clinging to a leaf or a blade of grass, occasion- 

 ally we see the caterpillar of the milkweed but- 

 terfly, its plump body banded with yellow, black, 

 and white. These caterpillars come from eggs de- 

 posited by the butterfly upon the upper surface of 

 the new leaves of the family food-plant (usually a 

 milkweed). In about four days the caterpillar 

 hatches, and spends the next two or three weeks, 



120 



