The Nest-building Odynerus 



cases, at irregular intervals, the same par- 

 titions, the same round disks of fine earth, 

 of mud gathered wet on the brink of an 

 irrigation-ditch or stream. Judging from 

 the appearance of the materials, I imagine 

 that the Odynerus has fetched her clay from 

 the banks of the neighbouring torrent, the 

 Aygues. 



Identity of construction is maintained 

 even in details which I had at first regarded 

 as a feat peculiar to the Osmia. Let us 

 recall her compartment-building secret. If 

 the reed be of middling diameter, the cell is 

 first stocked with provisions and next 

 bounded in front with a partition run up 

 then and there, without any pause in its 

 construction. If the reed, without being ex- 

 cessively wide, be of a certain thickness, the 

 Osmia, before stowing away the victuals, 

 gets to work on the front partition, pro- 

 viding it with an opening at the side, a sort 

 of service-hatch, through which the honey 

 is more easily discharged and the egg more 

 easily placed in position. Well, this secret 

 of the service-hatch, which was revealed to 

 me by the glass tube, is as well-known to 

 the Odynerus as to the Osmia. She, too, 

 in the bigger reeds, finds it to her ad- 

 vantage to close the larder in front before 

 189 



