30 INSECT ARCHITECTURE. 



The sort of sand-bank which it selects is hard and 

 compact ; and though this may be more difficult to 

 penetrate, the walls are not Hable to fall down upon 

 the little miner. In such a bank, the mason-wasp 

 bores a tubular gallery two or three inches deep. 

 The sand upon which Reaumur found some of these 

 wasps at work was almost as hard as stone, and 

 yielded with difficulty to his nail ; but the wasps dug 

 into it with ease, having recourse, as he ascertained, 

 to the ingenious device of moistening it by letting 

 fall two or three drops of fluid from their mouth, 

 which rendered the mass ductile, and the separation 

 of the grains easy to the double pickaxe of the little 

 pioneers. 



When this wasp has detached a few grains of the 

 moistened sand, it kneads them together into a 

 pellet about the size of one of the seeds of a goose- 

 berry. With the first pellet which it detaches, it 

 lays the foundation of a round tower, as an out- 

 work, immediately over the mouth of its nest. 

 Every pellet which it afterwards carries off from 

 the interior is added to the wall of this outer 

 round tower, which advances in height as the 

 hole in the sand increases in depth. Every two or 

 three minutes, however, during these operations, it 

 takes a short excursion, for the purpose, probably, of 

 replenishing its store of fluid wherewith to moisten the 

 sand. Yet so little time is lost, that Reaumur has 

 seen a mason-wasp dig in an hour a hole the length 

 of its body, and at the same time build as much of its 

 round tower. For the greater part of its height 

 this round tower is perpendicular ; but towards the 

 summit it bends into a curve, corresponding to the 

 bend of the insect's body, which, in all cases of 

 insect arcliitecture, is the model followed. The 

 pellet which form the walls of the tower are not 

 very nicely joined, and numerous vacuities are left 



