BEES OF GREAT BRITAIN. 161 



ing on her operations as detailed above, another was tunneling 

 in a horizontal rail : here no lower opening was required, the 

 bee pushed the chips out at the entrance, and as no outlet was 

 necessary at the end of the tunnel, the bee in this case made 

 none. 



There is still another species of this genus whose habits are 

 so different to the rest, that our admiration of the ingenuity 

 of these bees is greatly increased when we consider its curious 

 details, and reflect upon the degree of care and foresight exhi- 

 bited by the provident parent, this is the Osmia parietina, a bee 

 only found in the northern parts of this country. This species 

 selects the underside of a slate or stone lying on the ground, and 

 having a hollow space beneath ; to the stone the bee attaches 

 the little balls of pollen. A stone of this kind was found at 

 Glen Almond, Perthshire, on the Grampians, 800 feet above the 

 level of the sea, by Mr. J. Robertson, who, on turning it up, 

 observed a mass of cocoons ; although he was not much ac- 

 quainted with entomology, still he knew them to be the produc- 

 tion of some insect; he presented the stone to the British 

 Museum, and it was placed in my hands for observation. The 

 size of the stone was 10 inches by 6 ; the number of cocoons 

 attached to it two hundred and thirty : when first discovered, 

 about one-third of them were empty ; this was in the month of 

 November. In the beginning of the following March, a few 

 males made their appearance, and shortly afterwards some fe- 

 males ; they continued to come forth occasionally until the end 

 of June ; at this time there remained thirty-five undeveloped 

 cocoons ; on opening one or two of them, they proved to contain 

 active larvae ; these I carefully closed, and left the whole undis- 

 turbed until the following April, at which time, on examination, 

 they proved to be still in the larva state ; but at the end of May 

 they changed to pupae, and about the end of June began to come 

 forth perfect insects. This, then, was the result a portion of 

 a deposit of eggs made in 1849 had been three years in arriving 

 at maturity : when found, one-third were developed ; the follow- 

 ing year a second brood came forth, and whilst in my possession 

 a third. In the first instance, the whole deposit was subject to 

 the same influences, and had produced larvae ; what was the 

 cause of the retarded development of the rest, it were vain to 

 attempt to determine. 



The Osmia parietina is subject to the parasitical attacks of a 

 species of Chrysis, which destroys them in the larva state. The 

 Chrysis obtained from the cocoons of this bee is a new spe- 

 cies, closely allied to the C. Austriaca. A chalcididous insect, 

 Monodontomerus dentipes, is parasitic on the larva of 0. bi- 



