POMPILIDAE 103 



shy and inclined to adopt defensive or even evasive tactics, the 

 result probably being that the wasp will be killed by the spider 

 during the night, that being the period in which the attacking 

 powers of the spider are more usually brought into play. 



It seems to be the habit of some Poinpilus to procure a victim 

 before they have secured a place for its reception ; and Fabre took 

 advantage of this fact, and made very interesting observations on 

 some points of the instinct of these wasps. Having found a 

 Pompilus that, after having caught a spider and paralysed it, 

 was engaged in making a retreat for its reception, he abstracted 

 the booty, which was deposited at the top of a small tuft of 

 vegetation near to where the Pompilus was at work. In this 

 case the burrow in course of preparation was subterranean, and 

 was formed by the Pompilus itself, which therefore could not, 

 while it was engaged underground, see what took place near it. 

 It is the habit of the wasp to leave its work of excavation from 

 time to time, and to visit the prey as if to assure itself of the 

 safety of this object, and to enjoy the satisfaction of touching it 

 with the mouth and palping it. Desirous of testing the wasp's 

 memory of locality, Fabre took the opportunity, while the Insect 

 was working at the formation of its burrow, of remoA'ing, as we 

 have said, the booty from the place where it had been deposited, 

 and putting it in another spot some half-yard off. In a short 

 time the Pompilus suspended work and went straight to the spot 

 where it had deposited its property, and finding this absent, 

 entered on a series of marches, counter-marches, and circles round 

 the spot where it had left the prey, as if quite sure that 

 this was really the place where the desired object ought to be. 

 At last convinced that the paralysed prey was no longer where 

 it had been placed, the Pompilus made investigations at a greater 

 distance and soon discovered the spider. Fabre recounts that its 

 movements then appeared to indicate astonishment at the change 

 of position that it thus ascertained to have occurred. The wasp, 

 however, soon satisfied itself that this was really the very 

 object it was seeking, and seizing the spider by the leg slightly 

 altered its position by placing it on the summit of a small tuft 

 of vegetation ; this latter proceeding being apparently always 

 carried out by this species of Pompilus. Then it returned to its 

 excavation, and Fabre again removed the spider to a third spot ; 

 the wasp when it next rested from its work made its Way 



