MASONS 73 



which protects her progeny from the insidious 

 attack of a deadly enemy. How like the operations 

 of the human bricklayer who piles a stack of bricks 

 within reach of his hand from which he can take 

 them as wanted for building his wall ! 



The " deadly enemy " referred to above is the 

 brilliant little Ruby-tail Wasp (Cbrysis ignita), whose 

 head and thorax are blue or green in different 

 aspects, and the hind body red and gold, the entire 

 body having a metallic polish that makes the little 

 creature glow and flash in the sunshine. These 

 wasps make no nests of their own, but are always 

 on the watch for more industrious species that are 

 provisioning theirs, and whilst the Mason is away 

 hunting they pop in and leave an egg of their own. 

 The Cbrysis grub sucks the grub of the Mason 

 Wasp dry, or in some cases eats up the food and 

 leaves the rightful occupant of the nest to die of 

 starvation. It appears to be mainly against the 

 Ruby-tail that Odynerus builds her temporary 

 towers ; but Wood Ants (Formica rufa) have in 

 some districts to be guarded against also. 



Some of these Mason Wasps of the same genus 

 (Odynerus) carry their labour-saving ideas farther, 

 and look out for defects in human masonry. Where 

 a chink has been left in the mortar they enter and 

 enlarge it, making it symmetrical as they would 

 have done had they begun the excavation. Others 

 adapt key-holes, nail-holes, or any other perfora- 

 tions that are large enough, or can be made large 

 enough by a little manipulation. In some cases it is 



