26 INSECT ARCHITECTURE. 



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 Eeaumur 

 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 numerous vacuities are left 

 between them, giving it the appearance of filligree-Avork. 

 That it should be thus slightly built is not surprising, for 

 it is intended as a temporary structure for protecting the 

 insect Avhile it is excavating its hole ; and as a pile of 

 materials, well arranged and ready at hand, for the com- 

 pletion 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 do^Ti as ex- 

 peditiously as it had been reared. Eeaumur thinks that, 

 by piling in the sand which has previouly been dug out, the 

 wasp intends to guard his 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 avIio 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 tlie approach of an enemy to the 

 citadel. Eeaumur 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 



