520 Mrs. M. E. Barber's Notes on the 



to complain of. When they had attained the full size of 

 their species, and had ceased to feed, they at once set out 

 upon their rambles in search of a suitable spot wherein to 

 assume their dormant or pupa state ; finding, however, 

 that their travels were circumscribed, they appeared some- 

 what puzzled what to be at, and after a fruitless search 

 for a " leafy-dwelling," several of them returned to the 

 orange leaves, and there suspending themselves upon the 

 small twigs, took up their common form and colour 

 (fig. 1) ; others went to the bottle-brush branch, and there 

 became pale yellowish-green pupre (fig. 6), of precisely 

 the same colour as the half-dried leaves. One of the 

 caterpillars in particular affixed itself upon the wooden 

 framework of the case, where the wood and the brick 

 came in contact with each other, and, to my surprise, 

 this caterpillar, after throwing off its bright green skin, 

 assumed the colours of both the wood and tlie brick, its 

 under-side resembling that of the wood to which it was 

 attached (fig. 3), and the upper side that of the adja- 

 cent brick-work (fig. 4). So perfect was the assimi- 

 lation, that at first glance I failed to detect the pupa in 

 its altered condition, and looked upon the floor of the 

 case to see if the caterpillar had fallen. Some days later 

 another specimen affixed itself to the Avooden frame of 

 the case, and then became a yellowish pupa (fig. 5), of 

 the same colour as the wooden fi-ame. I then tried an 

 experiment by suiTounding one of the caterpillars with 

 a piece of scarlet cloth, but the creature failed to imitate 

 this brilliant hue ; the coloured spots upon the pupa were, 

 however, of a brighter red than those upon pupa No. 1 

 (fig. 1), otherwise I could observe no difference. The 

 season was now far advanced, there was no time for further 

 experiments ; I had succeeded in obtaining four different 

 colours, — the dark green pupa of the orange tree, the pale 

 yellow green of the bottle-brush, the yellow of the wooden 

 frame, and the purple and yellow, when the colours came 

 in contact. In its natural state I have ever found the 

 pupa of P. Nireus to be true to the colour of the leaves 

 of its food plant. 



I do not consider the changes described in this paper 

 to be merely accidental ; it is sufficiently evident that they 

 are of a conservative nature, — a protection to the butterfly, 

 during its helplessness as a pupa, from the ravages of 

 insectivorous creatures, to which a bright-green pupa 

 upon a dark-brown surface would be greatly exposed. 



