THE MASON BEE. 277 



Formidable enemies Mutual contests. 



whole group a common covering, made with 

 coarser grains of sand; so that at length the nest 

 becomes a mass of mortar, so hard as not easily 

 to be penetrated even by the blade of a knife. 



We may naturally suppose, from the hard- 

 ness of the materials with which the mason, 

 bee constructs her nest, and from the indus- 

 try and dexterity which she employs to pro- 

 tect her progeny from enemies of every kind, 

 that the young would be in perfect safety, 

 and that their castle would be impregnable. 

 But, notwithstanding all these precautions, they- 

 are often devoured by the larvae of a peculiar 

 species of ichneumon fly, the eggs of which are 

 deposited in the cells before the bee has com- 

 pleted them. But they have an enemy even still 

 more formidable than the ichneumons. A spe- 

 cies of beetle insinuates its egg into an unfinished 

 cell : from this proceeds a strong and rapacious 

 grub, armed with prodigious fangs, which often 

 pierces through every cell in the nest, and suc- 

 cessively devours all the inhabitants. They have 

 also enemies among themselves, and their nests, 

 which sometimes last for several seasons, are 

 .often the cause of desperate conflicts. When 

 one insect has taken possession of a nest, and is 

 gone abroad in quest of materials to repair it, 

 another will frequently come to seize it. When 

 these two meet, a battle invariably ensues. This 

 is always fought in the air. Sometimes the two 

 ibees fly with such rapidity and force against each 



