The Leaf-cutters 



der the least pressure of the fingers, the cylin- 

 der breaks up into equal sections, which are 

 so many compartments independent of their 

 neighbours as regards both floor and lid. 

 This spontaneous break-up shows us how the 

 work is done. The method agrees with those 

 adopted by the other Bees. Instead of a 

 general scabbard of leaves, afterwards sub- 

 divided into compartments by transverse par- 

 titions, the Megachile constructs a string of 

 separate wallets, each of which is finished be- 

 fore the next is begun. 



A structure of this sort needs a sheath to 

 keep the pieces in place while, giving them the 

 proper shape. The bag of leaves, in fact, as 

 turned out by the worker, lacks stability; its 

 numerous pieces, not glued together, but sim- 

 ply placed one after the other, come apart 

 and give way as soon as they lose the support 

 of the tunnel that keeps them united. Later, 

 when it spins its cocoon, the larva infuses a 

 little of its fluid silk into the gaps and solders 

 the pieces to one another, especially the 

 inner ones, so much so that the insecure bag 

 in due course becomes a solid casket whose 

 component parts it is no longer possible to 

 separate entirely. 



241 



