248 THE BIOLOGY OF INSECTS 



Tetramorium cespitum ; its habits are described by Forel 

 (1874), J^i^et (1897), Wheeler (1910), and others. The 

 males are wingless, and pairing must therefore take place 

 in the nest of Tetramorium, whence the young winged 

 females emerge in summer, and after casting their wings, 

 enter other Tetramorium nests, where they are received by 

 the workers, which ultimately kill their own queen and 

 devote themselves to attendance on the Anergates grubs. 

 The Anergates queen displays, as her eggs develop, a greatly 

 swollen abdomen, on which the sclerites become widely 

 separated by tracts of pale flexible cuticle, as in a '* replete " 

 worker honey-ant or a queen-termite. The Tetramorium 

 community that harbours Anergates must ultimately die 

 out since the workers have assassinated their mother. The 

 conditions of the permanent social parasitism among ants 

 are most remarkable both as regards the degeneration of the 

 parasite, and the apparently unnatural behaviour of the 

 host- workers. Wheeler agrees with Emery in considering 

 the mode of life of the temporarily parasitic ants to have 

 been derived from the slave-raiding habit, which seems 

 itself to have arisen as a specialisation of predaceous feeding. 

 The degeneration of habit noticeable in the " slavers " is 

 emphasised among the temporary parasites, while the per- 

 manent parasites have no longer a worker caste. Wheeler 

 calls attention to the extreme rarity of species of the last 

 group ; they are " so very scarce that they must be on the 

 very verge of extinction — a fact which shows that parasitism, 

 so far as race is concerned, is anything but a promising or 

 profitable business." It is noteworthy that nearly all the 

 slavers and social parasites among the ants are closely 

 related to their hosts, as the parasitic wasps and bees are, 

 so that for the ants also that practise such habits we may 

 infer a common origin with the creatures which they oppress 

 or exploit. 



Ants, more than all other insects, furnish examples, 

 numerous and varied, of association with insects of other 

 orders and creatures of other animal classes which inhabit 

 their nests and share in their social life as guests of the com- 



