THE OSMIA LEUCOMELANA. 109 



Five or six cells are made in each branch, and the perfect in- 

 sect appears about the month of June. 



Several species select localities even more remarkable, and 

 make their nests in -the empty shells of snails. The common 

 banded snail is a favourite with these bees, and in the British 

 Museum may be seen a whole series of such nests. The number 

 of cells necessarily varies with the size of the snail shell and the 

 number of its whorls, but on the average four or five cells are 

 found in each snail shell. The process of forming the cells is 

 very simple. First, the bee deposits a quantity of pollen and 

 honey, then she places an egg upon the pollen, and then she 

 makes a partition with vegetable fibres torn by her teeth and 

 kneaded firmly together. Lastly, the whole opening of the cell 

 is closed by a wall formed of clay, tiny bits of stick, and small 

 stones, and then the bee goes off in search of another shell. 

 These shells may often be found under hedges, in moss, hidden 

 by grass, and on examination the nests of bees will frequently 

 be seen in them. 



When the Osmia burrows into wood, she sets to work in a 

 very deliberate manner. ' A bee,' writes Mr. F. Smith, ' is ob 

 served to alight on an upright post, or other wood suitable for 

 its purposes. She commences the formation of her tunnel, not 

 by excavating downwards, as she would be incommoded with 

 the dust and rubbivsh which she removes ; no, she work np7vards^ 

 and so avoids such an inconvenience. When she has proceeded 

 to the length required, she proceeds in a horizontal direction to 

 the outside of the post, and then her operations are continued 

 downwards. She excavates a cell near the bottom of the tube, 

 a second and a third, and so on to the required number. The 

 larvag when full fed have their heads turned upwards. The 

 bees which arrive at their perfect condition, or rather those 

 which are first anxious to escape into day, are two or three in 

 the upper cells — these are males ; the females are usually ten 

 or twelve days later. This is the history of every wood-boring 

 bee which I have bred, and I have reared broods of nearly 

 every species indigenous to this country.' 



