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Bombus terrestris — an underground builder — are the 

 most numerous. One such nest he found to 

 contain 107 males, 560 females, and 180 workers; 

 a surface builder's nest — of Bombus sylvarum or B. 

 agrorum — would contain about half these numbers 

 of inmates. 



The empty cocoons from which came the first 

 batch of workers are utilized by them for the storage 

 of pollen, and by some species as honey-pots for 

 the immediate use of the commonwealth. We 

 have mentioned the readiness of the underground 

 builders to adapt a mouse's nest and run to their 

 own purposes ; and the surface builders are not 

 above similar economy of labour. We have found 

 them making use of a field vole's nest. They are 

 not likely to take possession of such places before 

 they have been abandoned by the original owners, 

 for mice are great enemies to the brood, though 

 they know better than to make an attack when the 

 bees are at home. 



Smith has recorded an instance of Bombus 

 agrorum taking possession of a wren's nest that 

 was occupied by a clutch of the bird's eggs. Possibly 

 the bee thought they were cocoons ; anyway, 

 she heaped up her collected pollen among them, 

 and so disgusted the wren by her action that she 

 abandoned her eggs, and it is probable built a new 

 nest elsewhere. Mr. Sladen mentions a double 

 case of adaptation. A mouse had utilized a cast- 

 off shoe as a nesting-place, and after the mouse had 

 done with it B. agrorum adapted the mouse- nest 



