JOINTED-LIMBED ANIMALS AS MESSMATES 175 
Insects (Insecta) as Messmates.—It will be ‘convenient to 
limit our attention to Bees and Ants, remembering that both 
belong to an order (Hymenoptera—Membrane-winged Insects) 
of which the members are distinguished by an extraordinary 
amount of specialization, associated with mental qualities of no 
mean order. 
Bees as Messmates.—Many species are known of what may 
be called, for want of a better word, Lodger Bees (Psithyrus), 
each kind of which lives in the nest of some sort of Humble-Bee 
(Bombus). In nearly all such cases the guest closely resembles 
its entertainer in appearance, and the two dwell together in a 
perfectly friendly way. The arrangement is of a one-sided nature, 
for the lodger not only has free quarters, but also makes free use 
of the provisions stored up by the industrious humble-bee, which, 
however, is not directly harmed by the association. But as a 
result of the raids made upon the larder by its lazy lodger, it is 
not able to rear nearly so many young ones as would otherwise 
be the case. A nest of a species of Humble-Bee (Bomédus varia- 
bits), examined by Hoffer in early autumn, contained only a 
queen and fifteen workers, together with eighteen Lodger-Bees 
(Psithyrus campestris), of which eight were females. But for the 
strain on the commissariat there would, it was estimated, have 
been 200 humble-bees in the colony, or even more. 
Ants as Messmates.—Occasion has already been taken to 
note the curious relations which exist between Ants and Aphides, 
the latter being fed and tended in return for their services as 
“cows” (see p. 119). Even more extraordinary are the habits 
of certain Slave-making Ants, which press other ants into their 
service, employing them in all the varied duties of the nest. 
The slavers conduct organized raids from time to time, in order 
to keep up the number of their dependants, and it must be said 
that these take very kindly to their enforced labours. A notable 
European example is afforded by the large Amazon Ant (Pody- 
ergus rufescens), which enslaves the small Brown Garden Ant 
(Formica fusca). The following graphic account of the matter 
is given by Newman (in Ax ILntroduction to the History of 
Insects), and some of the details are set forth in fig. 1126:— 
“The most remarkable fact connected with the history of ants is 
the propensity possessed by certain species to kidnap the workers 
of other species, and compel them to labour for the benefit of the 
