Instinct and Discernment 



pine. The list of the sites that suit her would 

 almost form a complete catalogue of the 

 ligneous flora. 



The variety of places wherein the insect in- 

 stals itself, so eloquent of the part played by 

 discernment in their selection, becomes still 

 more remarkable when it is accompanied by a 

 corresponding variety in the architecture of 

 the cells. This is more particularly the case 

 with the Three-horned Osmia, who, as she 

 uses clayey materials very easily affected by 

 the rain, requires, like the Pelopa^us, a dry 

 shelter for her cells, a shelter which she finds 

 ready-made and which she uses just as it is, 

 after a few touches by way of sweeping and 

 cleaning. The homes which I see her adopt 

 are especially the shells of Snails that have 

 died under the stone-heaps and in the low, un- 

 mortared walls which support the cultivated 

 earth of the hills in shelves or terraces. The 

 use of Snail-shells is accompanied by the no 

 less active use of the old cells of both the 

 Mason-bee of the Sheds and of certain 

 Anthophorae (//. pilipes, A. pariet'ma and A. 

 personata) . 



We must not forget the reed, which is 

 highly appreciated when — a rare find — it ap- 



205 



