AMONG THE TOILERS 203 



insects are most plentiful towards the middle of 

 June, but many are later in development, probably 

 because they were reared in a cooler situation than 

 the others, for the whole brood generally issues 

 from its nest within the space of a week. 



When flies, butterflies, and similarly thoughtless 

 insects are hatched, they crawl out of their chry- 

 salis skins, dry their wings, and fly away. But it 

 is not so with the mason wasp. It appears that 

 she must learn how her home was constructed, 

 for she crawls over and examines every part of it 

 before setting up an establishment of her own. 



The female alone toils, and she labours cease- 

 lessly. The site of a new nest is very carefully 

 selected, and building operations are then com- 

 menced. The builder seems to know that the 

 strength of her edifice will depend on the 

 character of the materials used, for she tries many 

 spots on the garden path before deciding where 

 her quarry shall be excavated. She remembers 

 the exact spot chosen, and returns to it time after 

 time with unerring precision. She also seems to 

 know where to find necessary liquid for moisten- 

 ing the mortar, which is generally obtained quickly 



