DISTRIBUTION AND ADJUSTMENT in 



and runs in, inclining downward from the mouth. It is three 

 or four inches long. In digging it the wasp cannot throw the 

 sand out from the far end at once, but must move it several times, 

 about an inch each time, by the method already described. 

 While digging she comes to the mouth of the burrow frequently, 

 backing out always, stands still a moment, and goes back to 

 work unless some inadvertent movement of the observer scares 

 her, when she flies away to return shortly if all is quiet. The 

 burrow completed, the mouth is closed, the wasp throwing the 

 earth into it from all sides, changing her position repeatedly to 

 do this. Then she flies off to secure insects with which to stock 

 her excavation. She apparently uses dead flies chiefly, which 

 she secures from the dead insects washed up by the waves along 

 shore. On her return with a fly she drops it on the sand near 

 the nest site. She runs around erratically to locate the hole 

 exactly, uncovers the opening, quickly seizes the fly, and goes 

 in with it. She reappears almost immediately, covers the open- 

 ing, and flies off for another. When four or five flies are secured 

 she remains in the burrow somewhat longer with the last, 

 emerges backward as usual, and then spends considerable time 

 closing the opening and pawing the sand about until all trace 

 of her work is obliterated. Presumably the egg or eggs are laid 

 in the burrow, possibly on the flies that are to serve as food for 

 the growing grubs. The most remarkable thing in this whole 

 story is that when, after many days, the young female emerges 

 from her gravelike nursery she shortly proceeds to dig a hole, 

 stock it with flies, lay the eggs, and cover up the nest with con- 

 summate skill, yet she has received no instruction, has not even 

 seen the job done. Somehow in her nervous system is registered 

 the racial instinct, and she goes through the whole performance 

 unerringly, untaught. 



