SOME SOCIAL WASPS 263 



the others, gave no evidence of such an impediment. These 

 two queens returned to the nest, even under the handicap 

 of being carried up the hill to the laboratory and down 

 again, quite out of the direct route to the point of release. 



Experiment Xa 



July 1 8. We have heard somewhere that bee-keepers 

 choose a hill-top for the location of an apiary because bees 

 when foraging will descend a hill, but, if the hive is in a 

 valley, they will never go to the hill-tops for nectar. Ma- 

 terial was available for an experiment to see if this prin- 

 ciple holds in Polities pallipes. Three wasps were taken on 

 top of the hill and liberated in the valley 150 feet below and 

 one-eighth mile distant, while from an out-house near the 

 point of their release, four wasps were taken and carried to 

 the top of the hill and liberated near the point where the 

 first lot had their nests. 



From the hill-top, the queen from nest 19 was used, the 

 one which in Experiment VI had made the one-eighth-mile 

 flight successfully over a country of level topography. This 

 wasp never returned ; despite her previous success on a level 

 plane, she failed to find her way home for the same distance 

 when it was uphill work. 



From nest 18 two workers, whose ages were 17 and 14 

 days respectively, were carried to the bottom of the hill with 

 the queen mentioned above, but neither of them returned. 



We are surprised that queen 19 failed to make the return 

 flight for so short a distance, and since the other two old 

 workers failed to return, we can readily suspect that the 

 hillside was a barrier, or that the region below their home 

 was completely unknown to them. 



Now "we shall consider the wasps which were taken in 

 the valley and carried to the hill-top. 



