274 THE WONDERS OF INSTINCT 



which is quickly shut by the inmate's mere withdrawal 

 into his house and as easily opened when the hermit goes 

 forth. With this system of closing, the abode becomes 

 inviolable; and the Drilus knows it. 



Fixed to the surface of the shell by an adhesive appa- 

 ratus whereof the Lampyris will presently show us the 

 equivalent, he remains on the look-out, waiting, if neces- 

 sary, for whole days at a time. At last the need of air 

 and food obliges the besieged non-combatant to show 

 himself: at least, the door is set slightly ajar. That is 

 enough. The Drilus is on the spot and strikes his blow. 

 The door can no longer be closed; and the assailant is 

 henceforth master of the fortress. Our first impression 

 is that the muscle moving the lid has been cut with a 

 quick-acting pair of shears. This idea must be dis- 

 missed. The Drilus is not well enough equipped with 

 jaws to gnaw through a fleshy mass so promptly. The 

 operation has to succeed at once, at the first touch: if 

 not, the animal attacked would retreat, still in full vigor, 

 and the siege must be recommenced, as arduous as ever, 

 exposing the insect to fasts indefinitely prolonged. Al- 

 though I have never come across the Drilus, who is a 

 stranger to my district, I conjecture a method of attack 

 very similar to that of the Glow-worm. Like our own 

 Snail-eater, the Algerian insect does not cut its victim 

 into small pieces: it renders it inert, chloroforms it by 

 means of a few tweaks which are easily distributed, if the 

 lid but half-opens for a second. That will do. The be- 

 sieger thereupon enters and, in perfect quiet, consumes a 



