The Homing of the Hymenoptera 39 



space of about eight inclies between each two.^^ Each 

 window was provided with two sliades, one extending 

 from the top to the middle, and one covering the lower 

 sash. On the west there were two widely separated 

 windows. One of these was kept open night and day. 

 For convenience, the windows on the north were num- 

 bered three, four, five and six. They were kept closed 

 at all times but the shades were manipulated in a variety 

 of ways. At the beginning of the experiment all shades 

 were down except the top shade of window four, which 

 was raised to the fullest extent. A mud-dauber wasp be- 

 gan a nest a little to the west of the upper left-hand cor- 

 ner of window four. After one cell had been about 

 completed, while the wasp was afield, the upper shade 

 of window four was lowered and the corresponding 

 shade of window five raised. This shifted a broad beam 

 of white light one window to the east. No other change 

 was made in the surroundings. If wasps are guided 

 home by the mysterious force for wliich Bethe contends, 

 no change should have been made in the behavior of this 

 wasp. Presently the insect returned and flew directly, 

 not to the nest, but a little to the west of the upper left- 

 hand corner of window five. She searched and searched, 

 but on that trip did not find the nest until the shades 

 were restored to their former position. To make a long 

 story short, for several days, the shades were manipu- 

 lated in a variety of ways. Each time a change was made 

 the wasp acted as though it was confused. Evidently 

 that Hymenopteron was using landmarks, of which the 

 beam of light was one. 



"Several of the walks of the Haines Nonnal School, 

 Augusta, Georgia, are separated from the adjacent flower 



•- Turner. C. H. The Homing of the Mud-Dauber. Biol. Bull., vol. 

 15, pp. 215-225. 



