WHEELER— THE PARASITIC ACULEATA. 23 



fusca or one of its varieties), and of carrying their larvse and pupae 

 home and permitting a certain number of them to hatch as " slaves," 

 so that the colony is maintained as an intimate mixture of two spe- 

 cies, at least for a considerable period. The queen Polycrgus, 

 however, kills the queen of the host colony whose nest she enters 

 and is adopted by the workers, and the slave-making, or dulotic 

 raids of her offspring are even more perfectly organized than in 

 sangninca, since Polycrgus in all its phases depends absolutely on 

 the slaves, or host workers for its food, the rearing of its young 

 and the construction of the common nest. It will be noticed from 

 the table (Table IV.) that all the slave-making, or dulotic parasites 

 belong either to the same genera as their hosts or to closely allied 

 genera, though the latter represent two different subfamilies. 



The recently fecundated queen of the temporary social para- 

 sites belonging to Formica species of the rufa, microgyna and ex- 

 secta groups, Bothriomyrmex, Lasius umhratiis and fuliginosus or 

 some species of Aphccnogaster, enters the nest of the host in a con- 

 ciliatory or at any rate non-aggressive manner, and after being 

 adopted by the workers, supplants the host queen, when she is killed 

 either by her own workers or by the parasite, which then proceeds 

 to produce her own brood to be reared by the host workers. The 

 offspring of the parasite, however, are not slave-makers, so that the 

 host workers gradually die off, leaving a pure and eventually flour- 

 ishing colony of the intrusive species. As shown in the table (Ta- 

 ble v.), all the temporary social parasites belong to the same genera 

 as their hosts, although these genera represent at least three differ- 

 ent subfamilies. 



The queen of the permanent social parasites enters the host col- 

 ony in the same insinuating and conciliatory manner as the tem- 

 porary social parasite and is definitively adopted in the same man- 

 ner after the host queen has been eliminated, but the rate of devel- 

 opment of the parasitic brood is very rapid, so that adult males and 

 females are produced within the lifetimes of the host workers. 

 This development of the sexual forms is the more accelerated be- 

 cause the worker caste has disappeared among the permanent social 

 parasites, which represent the culmination, or, more properly 

 speaking, the level of the greatest "degeneration" (specialization) 



