162 



THE CANADIAN ENTOMOLOGIST 



of the insects, helped itself to a meal at slight cost, pecking three 

 holes; one at 18, the other at 22.5 and the last at 30 cm., below the 

 top of the branch. Notwithstanding the precarious condition of 



the stalk, opened at not less than four points, 

 an insect thought it still serviceable and turned 

 it into a nest for its progeny — and it must be 

 owned, it did it well. 



One cell had been built at the bottom of 

 the canal. A piece of resin formed the floor, a 

 transverse partition of the same substance the 

 ceiling. Up to the present time my observa- 

 tions of Hymenoptera making their nests in 

 pithy plants have not yet furnished me with 

 any instances of an Apoid using resin for the 

 construction of partition. A bee, however, it 

 was, since some yellow powder, which remained 

 in a cell, was proved by microscopic examina- 

 tion to be pollen dust. In Europe the Heriades 

 truncorum L. is said to use resin for the same 

 purpose. 



After this first cell had been constructed, 

 the insect seemed to feel some misgivings con- 

 cerning the ultimate fate of its progeny, and left 

 unoccupied that section of the tunnel which ex- 

 tended as far as the lowest orifice bored by the 

 woodpecker. Here the wonderful instinct of 

 the bee reveals itself. It placed a first resin 

 stopper just below the level of this aperture, a 

 second one in the hole itself and a third above. 

 The stopper applied to the orifice closes it, but 

 imperfectly, and does not fill the whole tunnel 

 on the inside. But the two other pieces, above 

 and below, are quite cylindrical and close the 

 tube hermetically. All danger of intrusion from 

 below being thus removed, the bee constructed 

 five other cells above this barricade. Once more it did not make 

 use of the whole length of the tube between the two lateral openings, 

 but stopped its work 2.5 cm. below the second hole. A straight 



Fig.S. — a Holes made 

 by woodpecker. 



a' Id. covered with 

 pieces of resin fb')- 



b Pieces of resin 

 forming barricade. 



1-6 Cells separated 

 by resin partitions. 



