112 NATURAL HISTORY. [CH. VI. 



making- a tube ] why not simply heap up the sand 

 dug- out 1 When you see the work, you perceive 

 that it has scarcely more trouble in fixing the little 

 heap of mortar to the tube, than would be encoun- 

 tered in casting it out ; and it is more easy to 

 arrang-e the little mass in the cylindrical form, than 

 to construct a pyramid on a vertical wall, where for 

 the most part these tubes are found. 



" This tube has perhaps other uses. While the 

 wasp is absent, some ichneumon fly might come 

 and deposite in its nest an egg enclosing an insect 

 fatal to its young. The ichneumon will not so 

 readily enter a hole, when, to approach it, it is neces- 

 sary to make a long journey, and pass a tube which 

 prevents it from seeing if the wasp be absent. I 

 have observed one, which, after much hesitation, 

 turned and re-turned around the mouth of the tube, 

 and at last ventured in ; I also saw that this was 

 very mal a propos, for the wasp happening to be at 

 home, presented itself before the ichneumon, who 

 had believed it out of the way, so that there was 

 nothing left for the latter but to take speedily to 

 flight." 



If the hole be opened after the wasp has closed it, 

 it will be found filled with a number of caterpillars, 

 neatly rolled and packed together, but these, though 

 alive, have not the power of motion. Thus, from 

 the moment it is evolved from the egg, the little 

 carnivorous off'spring of the wasp can attack its 

 prey, and eat into them without any danger or dis- 

 turbance from creatures, which, in comparison to 

 itself, are giants in size. 



Being lodged at the bottom of the cell, with a 

 dozen worms packed up over its head, the larva of 

 the wasp begins to attack the one immediately 

 above ; it sucks with such avidity, that Reaumur 

 experienced some difficulty in withdrawing it from 

 the caterpillar. Indeed, all that the voracious worm 

 has to do, until the period of its metamorphosis, is 



