1 62 C. H. TURNER. 



nest was so sliallozv that only half of a wasp could be hidden in it; 

 in others the burrow ivas just deep enough to include the ivlwlc of 

 the wasp. Invariably the wasp removed the bits of weed and 

 deposited them on the ground near by. Sometimes the wasp re- 

 moved the weed stem or stems immediately ; at others she continued 

 excavating for a short time and then removed the foreign sub- 

 stance. It seems as though she removed the stems as soon as they 

 greatly hampered her movements. 



EXPERIMENTS WITH CATERPILLARS. Home-coming wasps were 

 robbed of their prey until I had collected a dozen paralyzed cater- 

 pillars. Burrow's in two stages of completion were selected: those 

 that were just deep enough to half conceal the -worker and tJwsc 

 tJiat were sufficiently deep to just hide the wasp. While the wasp 

 was gone for water one of tJie caterpillars would be placed in the 

 burrow and the nest watclicd until the wasp icsumcd her excavat- 

 ing. This was repeated over and over until the twelve caterpillars 

 had been used. With the exceptions of touches of individuality 

 the behavior was invariably the same. The wasp always removed 

 the caterpillar from the nest, flew with it to the weed-infested field, 

 and returned empty-handed. In some cases the wasp flew away 

 with the caterpillar as soon as arriving at the surface of the 

 ground ; more often she would climb some weed before flying 

 away. Sometimes the journey was preceded by a longer or shorter 

 flight of orientation, at others by none. The final flight was some- 

 times in one direction and sometimes in another, but always in the 

 direction of the weed-infested field. Why did these wasps react 

 so differently toward the several classes of objects? When pellets 

 of earth were dropped into the nests, the wasps either flew and 

 scattered them or walked and deposited them in piles ; when short 

 pieces of weed stems were placed in the burrows, the wasps de- 

 posited them on the ground adjacent to the nest ; when paralyzed 

 caterpillars were placed in the holes, the wasps flew with them to 

 the insect-infested field, which was several yards away. I confess 

 that every time a wasp flew away with a caterpillar it gave me an 

 intellectual thrill ; but, to me, the reason for the behavior remains 

 a mystery. 



