384 THE MASON BEE, 



with honey, for the sustenance of its future Inha- 

 bitant. This being done, she deposits her egg* 

 finishes and covers her cell, and then proceeds to 

 the erection of a second, which she furnishes and 

 finishes in the same manner; and so on till the 

 work is completed. These cells are not placed 

 in any regular order : some are parallel with the 

 wall, others perpendicular to it, and others are in- 

 clined to it at different angles. This occasions 

 many empty spaces between the cells, which the 

 laborious architect fills up with the same kind of 

 cement, and then bestows on the 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. 



These nests, which sometimes last for several sea- 

 sons, are often the cause of des'perate conflicts. 

 When one insect has taken possesion of a nest, and 

 is gone abroad in quest of materials to repair it, ano- 

 ther will frequently come to seize it. When these 

 two meet, a battle invariably ensues. This is al- 

 ways fought in the air. Sometimes the two bees 

 fly with such rapidity and force against each other, 

 that both fall to the ground. But, in general, like 

 birds of prey, the one endeavours to rise above 

 the other, and to give a downward blow. To avoid 

 the stroke, the undermost, instead of flying forward, 

 or laterally, is frequently observed to fly backward 

 This retrograde flight is likewise performed occasi- 

 onally by the common house-fly, and some other in- 

 sects, though we are unable to perceive what sti- 



3 



