NETTLE TORTOISE-SHELL BUTTERFLY. 129 



when they throw out from their tails a web, by which 

 they suspend themselves under the leaves, or on the 

 stalks of nettles, and are transformed into chrysalids. 

 These are at first of a green colour ; but, in the 

 course of two or three days, they change either into 

 a bright golden yellow, or greenish brown, approach- 

 ing nearly to bronze green. In this condition they 

 continue for about twenty days, when they burst 

 from their casement, and assume the perfect, or 

 butterfly state. 



