Bramble-bees and Others 



males. The incomplete series can teach us 

 nothing in this respect, for they are only frag- 

 ments starting we know not whence; and it 

 is impossible to tell whether they should be 

 ascribed to the beginning, to the end or to an 

 intermediate period of the laying. To sum 

 up : in the laying of the Three-pronged Os- 

 mia, no absolute order governs the succession 

 of the sexes; only, the series has a marked 

 tendency to begin with females and to finish 

 with males. 



The brambles, in my district, harbour two 

 other Osmias, both of much smaller size: O. 

 detrita, Perez, and O. parvula, DuF. 

 The first is very common, the second very 

 rare; and until now I have found only one 

 of her nests, placed above a nest of O. 

 detrita, in the same bramble. Here, instead 

 of the lack of order in the distribution of the 

 sexes which we find with O. tridentata, we 

 have an order remarkable for consistency and 

 simplicity. I have before me the list of the 

 series of O. detrita collected last winter. 

 Here are some of them: 



I. A series of twelve: seven females, be- 

 ginning with the bottom of the tunnel, and 

 then five males. 



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