The Tribulations of the Mason-bee 



ing the shredded leaves of a plant whose na- 

 ture is still uncertain. The same green paste 

 serves for the thick plug that closes the abode. 

 But in this case the insect does not use it un- 

 adulterated. To give greater power of re- 

 sistance to the work, it mixes a number of bits 

 of gravel with the vegetable cement. These 

 materials, which are easily picked up, are 

 lavishly employed, as though the mother 

 feared lest she should not fortify sufficiently 

 the entrance to her dwelling. They form a 

 sort of coarse stucco on the more or less 

 smooth cupola of the Chalicodoma; and this 

 unevenness, as well as the green colouring of 

 its mortar of masticated leaves, at once be- 

 trays the Osmia's nest. In course of time, 

 under the prolonged action of the air, the 

 vegetable putty turns brown and assumes a 

 dead-leaf tint, especially on the outside of the 

 plug; and it would then be difficult for any 

 one who had not seen them when freshly 

 made to recognize their nature. 



The old nests on the pebbles seem to suit 

 other Osmiae. My notes mention Osmia 

 Morawitzi, Perez, and Osmia cyanea, 

 KiRB., as having been recognized in these 

 dwellings, although they are not very assldu- 

 267 



