VI 



DEFENCES OF INSECTS 



229 



cumstance is altogether apart from sex, and seems 

 to exert no influence upon the future perfect 

 insects. Dimorphism is also present in perfect 

 insects, in the Lepidoptera especially in the females. 

 It occurs likewise among male spiders. As regards 

 ants and others of the social Hymenoptera, the 



FIG. 44. The pupa of a South 

 African Swallow-tailed Butterfly 

 (JPapilio nireus) attached to orange 

 tree, and corresponding in colour 

 to its deep green leaves ; from 

 Trans. Entom. Soc. 



FTG. 45. The pupa of 

 Papilio nireus at- 

 tached to wood -work, 

 the colour of which it 

 imitates ; from Trans. 

 Entom. Soc. 



individual differences of the females are most pro- 

 nounced. Here, however, the meaning is obvious 

 since each form is set apart for different labour, an 

 arrangement advantageous to the society, and conse- 

 quently to the species. The benefits that accrue from 

 larval dimorphism are difficult to determine, but we 



