THE SENSE OF DIRECTION IN WASPS. 215 



the nest dug, she was ready to go out and seek for her store of 

 provision and now came a most thorough and systematic study 

 of the surroundings. The nests that had been partly made and 

 then deserted had been left without any circling. Evidently 

 she was conscious of the difference and meant, now, to take all 

 necessary precautions against losing her way. She flew in and 

 out among the plants first in narrow circles near the surface of 

 the ground, and now in wider and wider ones as she rose higher 

 in the air, until at last she took a straight line and disappeared 

 in the distance. The diagram (PI. XII., fig. 1) gives a tracing 

 of her first study preparatory to departure. Very often after 

 one thorough study of the topography of her home has been 

 made, a wasp goes away a second time with much less circling 

 or with none at all. The second diagram (PL XII., fig. 2) gives 

 a fair illustration of one of these more hasty departures. To 

 some philosopher sitting in his study and reading learned works 

 upon instinct and reason, this may seem all foolishness, and cer- 

 tainly if he prefers to believe that the wasp is endowed with a 

 sense of direction, and that all this flying here, and circling 

 there, has nothing to do with her method of finding her way, 

 he is at liberty to do so, even if this does leave a rather large un- 

 explained residuum. 



If the examination of the objects about the nest makes no 

 impression upon the wasp, or if it is not remembered, she ought 

 not to be inconvenienced nor thrown off her track when weeds 

 and stones are removed and the surface of the ground is 

 emoothed over; but this is just what happens. Aporus fasciatus 

 entirely lost her way when we broke off the leaf that covered 

 her nest, but found it, without trouble, when the missing object 

 was replaced. All of the species of Cerceris were extremely 

 annoyed if we placed any new object near their nesting-places. 

 Our Ammophila refused to make use of her burrow after we 

 had drawn some deep lines in the dust before it. The same an- 

 noyance is exhibited when there is any change made near the 

 spot upon which the prey of the wasp, whatever it may be, is 

 deposited temporarily. "We learned from experience how im- 



