236 THE BIOLOGY OF INSECTS 



reared, according to Wheeler and others, by workers of 

 V. diabolica. The systematic relationship between these 

 apparently " cuckoo " wasps and their hosts is exceedingly 

 close, much closer than that between Pysithrus and Bombus. 

 G. H. Carpenter and D. R. Pack-Beresford (1903) showed 

 from a study of the male armature and the variation of 

 coloration and structural features in V. austriaca and 

 V. riifa that these tsvo species are much more nearly related 

 mutually than either is to any other British wasp, and that 

 each of the two forms varies towards the other as regards 

 these characters (Fig. 60B, i-io and I -X.). From a census 

 of the population of a nest in which the old queen was 

 an austriaca and the latest emerged members workers and 

 males of rufa, these observers concluded that the two 

 might reasonably be regarded as alternative forms of one 

 variable species, since an austriaca queen was apparently 

 the mother of individuals which were clearly referable to 

 rufa. Yet the occasional inquiline habit of one race of 

 Bombus on another, mentioned already in this chapter, lends 

 support to the accepted view that Vespa austriaca frequently 

 plays the part of a cuckoo-parasite on V. rufa. Certainly all 

 the facts combine to confirm Wheeler's generalisation that 

 inquilines among the aculeate Hymenoptera are always 

 nearly related to and genetically derived from their hosts. 



Turning from wasps and bees to ants, we come to con- 

 sider the niost remarkable of all social insects — in some 

 respects indeed the most remarkable of social animals, for 

 the ant-communit}^ may be organised and specialised, within 

 the limits imposed by the structural and psychic conditions 

 of its members, to a degree that challenges comparison with 

 the human commonwealth, so that the activities of ants 

 have been held up by moralists as an example to encourage 

 industrious effort among men. Modern students of the 

 ways of ants have the great advantage of being able to 

 consult the comprehensive treatises of W. M. Wheeler 

 (1910, see also 1923 and 1926) and A. Forel (1921), while 

 the habits of our British species have been well described 

 by H. K. Donisthorpe (1927). 



