THE MASON BEE. 27 



cocoon about the walls of its prison, which were quite hard and 

 smooth on the inside, probably owing to the movements of the 

 larva, and the consequent pressing of the sticky particles to the 

 walls. In a short time the opening made was closed over by a 

 very thin silken web. The cells, measured on the inside of the 

 hard walls, were .35 of an inch in length, and .15 in diameter. 

 The natural attitude of the larva is somewhat curved in its cell, 

 but if straightened, it just equals the 

 inside length of the cell. On the 31st 

 of July, two female bees came out, 

 having cut their way through the sides 

 of their cells." In three other cells 

 " several hundred minute Ichneumons 

 (Anthophorabia megachilis) were 

 seen, which came forth as soon as the 

 cells were opened." 



The habits of the little blue or green 

 Mason bees (Osmia) are quite varied. 

 They construct their cells in the stems 

 of plants, and in rotten posts arid trees, 

 or, like Andrena, they burrow in sunny 

 banks. A European species selects 

 snail shells for its nest, wherein it 

 builds its earthen cells, while other 

 species nidificate under stones. Curtis 

 found two hundred and thirty cocoons 

 of a British species (Osmia paretina), 

 placed on the under side of aflat stone, 

 of which one-third were empty. Of 

 the remainder, the most appeared be- 

 tween March and June, males appear- 

 ing first; tjiirty-flve more bees were 

 developed the following spring. Thus 

 there were three successive broods, 26. Nest of Osmia 



for three succeeding years, so that these bees lived three years 

 before arriving at maturity. This may partly account for insect 

 years, which are like "apple years," seasons when bees and 

 wasps, as well as other insects, abound in unusual numbers 



Mr. G. K. Waterhouse, in the Transactions of the Entomo 

 logical Society of London, for 1864, states that the cells of 

 Osmia leucomelana "are formed of mud, and each cell is built 



