SEPTEMBER 235 



queen's labours of egg-laying, might become exceedingly 

 populous, but for an extraordinary blindness on the part 

 of these clever insects. Every species of Bombus is 

 shadowed by a corresponding species of Psithyrus, bees 

 of another genus, and of most reprehensible habits. 

 Yellow-tailed bumbles attract yellow-tailed Psithyrus, 

 red- tailed bumbles have to entertain red-tailed Psithyrus ; 

 and so closely do the two genera resemble each other that 

 the older naturalists failed to distinguish the difference 

 between them. Bombus is the most industrious of all 

 bees, working far longer hours than the honey-bee ; Psi- 

 thyrus works not at all. Late in the day, hours after the 

 exemplary Bombus has been at work, he may buzz forth 

 among the sunny flowers for a short tune ; but most of 

 his time he spends among his host's honey-tubs, stuffing 

 himself with sweets which don't belong to him, and 

 encouraging his wives to lay as many eggs as possible 

 in the house and among the good things of Bombus. He 

 grows more portly than Bombus, who can only rear a 

 fraction of its Iarva3, because Psithyrus eats all the food 

 intended for them. Hoffer found that a nest of Bombus, 

 if protected from Psithyrus, increased to two hundred 

 souls I mean bumbles whereas in another, not so pro- 

 tected, he counted on the first of September only a queen 

 Bombus with fifteen workers and eighteen gluttonous 

 Psithyrus, whereof eight were females. 



The strangest part of the story is that the hosts live on 

 the friendliest terms with their ignoble guests, working as 

 heartily to provide delicacies for them as for their own 

 young. So true is the verse, though in a sense never 

 suspected by the author : 



' Sic vos non vobis mellifieatis apes.' 



