78 OF THE SENSES OF 



belligerents, no one disturbing its neighbour, though 

 they stood side by side, and almost touching one 

 another. They were, indeed, too intent on quenching 

 their thirst to think of attack or defence. We 

 remarked, in the autumn of 1829, a similar congre- 

 gation of the same species of butterfly on the watered 

 roads in the vicinity of London. They do not seem 

 to be more choice in the quality of their water than 

 bees, who, most naturalists tell us, prefer that which 

 is stagnant and putrescent."* 



It is remarkable that some insects feed upon 

 substances which are poisonous to other animals ; for 

 example, the Caterpillar of the Papilio cupido feeds 

 on the leaves of tobacco, which proves a deadly 

 poison to most of the mammiferous animals, and 

 is even destructive to many of the insect tribes. 



OF SMELL. 



THERE can be little doubt that the sense of smell 

 is enjoyed by most insects in a high degree of 

 perfection. Mr Rennie remarked, that, in a narrow 

 garden, enclosed with stone walls, about fifteen 

 feet high, at Havre de Grace, every butterfly which 

 passed over it was sure to visit the blossoms of an 

 Alpine blue nettle, (the Centcturea montanea.} This is 

 the more remarkable, as that flower is known to have 

 but little effect on the olfactory nerves of the human 



* REAUMUR, v. p. 697. 



