Bramble-bees and Others 



laid not only by the Osmlae but by a host of 

 other Bees fluctuates round about fifteen. 



Besides, when we consider that the active 

 life of these insects lasts hardly a month; 

 when we remember that this period of act- 

 ivity is disturbed by dark, rainy or very 

 windy days, during which all work is sus- 

 pended; when lastly we ascertain, as I have 

 done ad nauseam in the case of the Three- 

 horned Osmia, the time required for build- 

 ing and victualling a cell, it becomes obvious 

 that the total laying must be kept within nar- 

 row bounds and that the mother has no time 

 to lose if she wishes to get fifteen cells satis- 

 factorily built in three or four weeks inter- 

 rupted by compulsory rests, I shall give some 

 facts later which will dispel your doubts, If 

 any remain. 



I assume, therefore, that a number of eggs 

 in the neighbourhood of fifteen represents the 

 entire family of an Osmla as It does of many 

 other Bees. 



Let us consult some other complete series. 

 Here are two: 



I 2 3 4 5 6 7 8 9 10 II 12 13 

 FFMFMFMFFF FMF 

 FMFFFMFFMF M 



96 



