Bramble-bees and Others 



fixed? She can only do so by abandoning the 

 arrangement in two consecutive rows and ac- 

 commodating her laying to the varied ex- 

 igencies of the home. Either she finds it 

 impossible to make an economical use of the 

 old nest, a theory refuted by the evidence, or 

 else she determines at will the sex of the egg 

 which she is about to lay. 



The Osmiae themselves will furnish the 

 most conclusive evidence on the latter point. 

 We have seen that these Bees are not gen- 

 erally miners, who themselves dig out the 

 foundation of their cells. They make use 

 of the old structures of others, or else of 

 natural retreats, such as hollow stems, the 

 spirals of empty shells and various hiding- 

 places in walls, clay or wood. Their work 

 is confined to repairs to the house, such as 

 partitions and covers. There are plenty of 

 these retreats; and the insect would always 

 find first-class ones if it thought of going any 

 distance to look for them. But the Osmia is 

 a stay-at-home : she returns to her birth-place 

 and chngs to it with a patience which it is 

 extremely difllicult to exhaust. It is here, in 

 this little familiar corner, that she prefers 

 to settle her progeny. But then the apart- 



13a 



