A WEEK WITH A MINING EUMENID. l6l 



higher portion of the maze would cover another nest in which the 

 wasp was still digging. In such cases the second wasp would con- 

 tinue to fly and scatter pellets (Fig. 4, /; 5, a). Thus, in the same 

 maze, I sometimes had one wasp walking and depositing pellets in 

 a pile or piles and another flying and scattering them. 



It is not claimed that these experiments predicate of wasps the 

 power of logical thinking; on that topic experiments of this type 

 are non-committal. However, they demonstrate conclusively that, 

 in Odynerus dorsalis Fab., the walking-to-deposit-the-pellet be- 

 havior is derived from the flying-to-scatter-the-pellets activity, in 

 response to a slight change in the environment. 



EXPERIMENTAL INTERFERENCE WITH THE WASP WHEN 



EXCAVATING. 



A series of experiments was conducted to test the reactions of 

 excavating wasps to objects dropped into their burrows. Three 

 kinds of objects were used in these experiments : pellets of dirt 

 (mineral matter), short pieces of weed stems (plant matter), live 

 caterpillars (animal matter). 



EXPERIMENTS WITH PELLETS. Pellets of dirt tJiat had been 

 removed from nests by certain wasps were dropped into the partly 

 excavated nests of other zvasps. In each case the wasp removed 

 the pellet and disposed of it in the usual manner. In each case 

 the return to the surface with the pellet was too quick to permit the 

 formation of one. 



EXPERIMENTS WITH BITS OF WEED STEMS. Stems of the weed 

 were cut into pieces about two inches long. These were placed in 

 the partly completed burroivs of the wasps. In sonic cases the 



FIG. 2. Showing a wasp that has been induced, by the maze, to walk and 

 deposit her pellets: b, maze; /, wasp carrying the pellet; g, opening- of the 

 nest ; /;, piles of pellets deposited by the wasp ; i, another wasp entering her 

 nest to oviposit. 



FIG. 3. Showing a wasp, that had been excavating inside the maze, flying 

 for water: a, the wasp flying for water; b, the maze; g, entrance to the nest; 

 h, piles of pellets deposited by the wasp; i, a wasp leaving her nest after ovi- 

 positing. 



FIG. 4. Showing a wasp preparing to fly off with a pellet: /, getting ready 

 for flight. 



FIG. 5. Showing a wasp flying away with a pellet: a, a wasp flying. 



