,j.oG 



ANTS. 



abdomen \vbicb are licked by the host with evident satisfaction. Not 

 only do these beetles themselves live as guests among the ants, but the 

 same is also true of their larvae. The larvae of Lomcchusa and Ate- 

 mclcs are reared by the ants like their own brood; they are licked, fed 

 with regurgitated food and before pupation covered or embedded in 



cells like their own larvae. 

 When the nest is disturbed 

 they are carried by the ants in 

 preference to their own larvae 

 and pupae to a place of safety. 

 The predilection of the ants 

 for these adopted larvae is all 

 the more remarkable because 

 they are the worst enemies of 

 the ant-brood and devour 

 enormous numbers of the eggs 

 and larvae of their hosts. 

 This brood parasitism, in fact, 

 causes the development of 

 abortive individuals interme- 

 diate between the female and 

 worker castes, and these inter- 

 mediates, which I have called 

 pseudogynes, gradually bring 

 about a degeneration of the 

 parasitized colonies. 



' Within the Lomechusa group an important ethological difference 

 obtains between Loineclntsa and Atcmclcs, inasmuch as the former is 

 homcecious, /'. e., the species of this genus have each but a single host 

 (a species of Formica ), in whose company they complete their whole 

 life-cycle; whereas the Atcmclcs are hetercecious, since as adult beetles 

 they live with M \nnica rnbra and a species of Formica, but have their 

 larvae reared only by the latter. The fact that Lomechnsa has only a 

 single host explains the more highly developed passive character of its 

 symphily. This is shown by the fact that the beetle is more affection- 

 ately treated by its normal hosts and is fed, not like an ant, but like an 

 ant-larva. The hetercecious character of the A fancies, which are com- 

 pelled twice during their life to change their normal hosts, once in the 

 spring when they migrate for reproductive purposes from Myrmica to 

 Formica, to have their larvae reared by the latter, and once in the 

 summer when they migrate from Formica to Myrmica for the purpose 

 of hibernating, enables us to explain the greater active perfection of 



(1 x 



FIG. 242. Worker, pseudogynes and de- 

 iilated queen of Formica incerta. (Original.) 



