234 THE BIOLOGY OF INSECTS 



Fig. 6oa. — Queen-Wasp (Vespa amtriaca), X3. 



she succeeds so well that the workers soon cease to show any 

 hostility towards her." After a time she kills the Bombus 

 queen, thereby cutting off any further production of workers, 

 but those already in the nest are enough for the tendance 

 of the intruder's eggs to which and to the resulting larvae 

 the workers " soon get reconciled " so that " they feed and 

 tend the Psithyrus brood with as much devotion as if it 

 were their own species." Sladen insists that the re- 

 semblance of a Psithyrus to a Bombus " is not merely 

 superficial but extends to nearly all the important details 

 of structure, so that it is impossible to avoid the conclusion 

 that Psithyrus has sprung from Bombus, and this at quite 

 a recent period in the history of Hfe." Here we find the 

 inquiline specialised in such a way as to bring the invading 

 queen into definite social contact with the host-workers, 

 so that these — not through any motive that can be truly 

 called '* devotion," but as a result of their normal, inherited 

 reflex tendencies — feed her young as though they were 

 their own sisters. 



Among the social wasps (Vespa) there are several species 



