ABILITY OF MUD-DAUBER TO RECOGNIZE OWN PREY 241 



part of her own unless she meant to clear them all out as though 

 they were contaminated ? Would other mother wasps act in 

 the same way under similar circumstances ? These questions 

 led us on to further experiments the following summer, with 

 many varied and surprising results. The observations were 

 made during a week's vacation, on wasps building in an old 

 barn at Lake View, Kansas. Only the details of each experi- 

 ment can give the reader a fair idea of their varied behavior. 



EXPERIMENTS 



Exp. 1. A new Pelopoeus cell was found already one-fourth 

 filled with spiders. When an opportunity occurred, I slyly 

 filled it high with spiders from another nest. The mother wasp 

 returned with a large spider, and spent some time in laboriously 

 cramming it in. Quite satisfied now with her store, she brought 

 balls of mud and duly closed up the cell. But while she was 

 gone for another load I picked open the seal and extracted part 

 of the contents. Arriving at the nest with the next pellet she 

 saw the injury and was alarmed, hurried out and threw the mud 

 away, returned and indignantly carried out the remaining spiders 

 one by one, her own as well as mine, until the nest was quite 

 empty. 



Exp. 2. While Pelopoeus was gone I stirred up the spiders 

 which she had placed in her cell and added one from another 

 nest. When she returned she promptly carried it out, and made 

 four more trips, each time carrying out one of her own capture, 

 until all were gone. Then, after a brief, unexplained absence 

 she came back and inspected the empty cell, fretted and ex- 

 amined and stood guard over it for an hour and a half all because 

 a few spiders had been disturbed. 



Upon returning three hours later I found the cell sealed. 

 I opened it and found just two medium-sized spiders, with an 

 egg attached to one. Thus this mother was so anxious about 

 her progeny that she carried out and rejected all of the spiders 

 which had been touched by human hand or forceps, and now 

 she sealed up the egg with only sufficient food to carry it half 

 through its larval life. 



Exp. 3. One day while collecting nests I removed a large 

 one from a shelf against the barn-wall. No sooner done than a 



