EVOLUTION OF INSECT INSTINCT. 107 



If we throw a spider that has been stung by a fellow- wasp at one 

 of these, it will nearly always be taken without hesitation, and 

 will often be stung again. The depositing and the laying of the 

 egg are done as if by habit ; and I may add that the hunter is not 

 dainty as to the freshness of his game. I have seen spiders of 

 eight days' standing accepted, and have repeated the experiment 

 so often that I can not suppose that the fact is accidental. It is 

 not a case of one opening a cell to deposit an egg because its own 

 has been stolen, or of digging into the partitions at the end of its 

 labors ; but what I relate happens almost regularly whenever oc- 

 casion offers. It may be said that the insect is obliged to deposit 

 its egg. Perhaps, but the necessity for ovipositing is singularly 

 elastic with my pompili, and is associated with the faculty they 

 have of stealing the game of their neighbor. 



A Pompilus viaticus has just drawn its spider into the cell. 

 It has deposited its egg and stopped up its hole. I offer it a new 

 spider, killed ; it is not the time for ovipositing, but the victim is 

 accepted and placed carefully by the side of the nest, the closing 

 of which is arrested. A new cell is dug out, the booty is drawn 

 into it, and receives an egg in its turn. 



I have often repeated this experiment with Pompilus viaticus 

 and pedinipes. I broke open the half-closed nest, and unfastened 

 the egg, and I have several times seen the spider taken up, car- 

 ried a little farther on, and the ovipositing begun again. 



So far I have told of experiments ; now I come to pure ob- 

 servation. Let us go at the beginning of September into a warm 

 gravelly quarry. We see many hymenoptera there, but the 

 pompilides dominate. They have chosen the most agreeable 

 quarter, the most sunny one in the city. Those which I observed 

 were the Pompilus rufijjes. They are a colony of crafty fellows, 

 constantly in motion, ferreting everywhere, sometimes on the 

 quest for a neighbor's spider, going into the holes which they find 

 to their taste to drive the proprietors from them. When they 

 have succeeded in stealing, they bury their spoil, if some other 

 thief does not interfere, and deposit an egg upon it. These thefts 

 are often the occasion of lively combats. I chanced to see two 

 of the largest of the band disputing over a spider. Hunters 

 and victim rolled like a ball along the gravel for four or five 

 yards. The contestants, which had not let go, tugged at their 

 prey like dogs wrangling over a bone. After a few minutes the 

 beaten one generally the less corpulent gave up the struggle. 

 The species, however, is not parasitic. The spider is in the 

 beginning the legitimate prey of one of the two, and I have, 

 besides, seen them hunting and ovipositing honestly in the same 

 quarry. 



Not only in the capture of the prey, but in the choice of the 



