302 WASPS AND THEIR WAYS 



into its hole and went to work vigorously 

 continuing the excavation. 



There are some species of the digger- 

 wasps that make their excavations in bricks 

 or in sand-banks that are almost as hard as 

 stone. These little miners are as careful 

 as the wood-borers not to leave chips 

 lying about to betray their presence to the 

 enemy. They dig out the hard brick or 

 sand with their jaws, moistening and soft- 

 ening it with liquid from their mouths, 

 and as soon as they have chiselled out a 

 fragment they fly to some distance and 

 drop it. They do not go in very far, 

 usually not more than two inches. Some- 

 times they line with clay the cave they 

 have excavated, and stop the opening also 

 with clay. 



There is a little miner-wasp in Europe 

 that uses the material it removes from its 

 burrow in a hard sand-bank to make a round 

 tower over its hole. The French naturalist 

 Reaumur watched these wasps at work 



