Mason-Wasps. 27 



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

 plenishing 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 

 architecture, is the model followed. The pellets which form 

 the walls of the tower are not very nicely joined, and numer- 

 ous vacuities are left between them, giving it the appearance 

 of filigree-work. That it should be thus slightly built is 

 not surprising, for it is intended as a temporary structure for 

 protecting the insect while it is excavating its hole, and as a 

 pile of materials, well arranged and ready at hand, for the 

 completion of the interior building, in the same way that 

 workmen make a regular pile of bricks near the spot where 

 they are going to build. This seems, in fact, to be the main 

 design of the tower, which is taken down as expeditiously as 

 it had been reared. Reaumur thinks that, by piling in the 

 sand which has previously been dug out, the wasp intends to 

 guard her progeny for a time from being exposed to the too 

 violent heat of the sun ; and he has even sometimes seen that 

 there were not sufficient materials in the tower, in which case 

 the wasp had recourse to the rubbish she had thrown out 

 after the tower was completed. By raising a tower of the 

 materials which she excavates, the wasp produces the same 

 shelter from external heat as a human creature would who 

 chose to inhabit a deep cellar of a high house. She further 

 protects her progeny from the ichneumon-fly, as the 

 engineer constructs an outwork to render more difficult the 

 approach of an enemy to the citadel. Reaumur has seen 

 this indefatigable enemy of the wasp peep into the mouth of 

 the tower, and then retreat, apparently frightened at the 

 depth of the cell which he was anxious to invade. 



The mason-wasp does not furnish the cell she has thus 

 constructed with pollen and honey, like the solitary bees, 

 but with living caterpillars, and these always of the same 



