THE HOMING OF THE MUD-DAUBER. 2ig 



Experiment i. 



T/ie loiver shade of window ninnbcr one was raised half way 

 and the top shade as far as it zvould go. While the zvasp was out 

 of the room, all the blinds of windozvs number tzvo to six were 

 closed except the upper shade of zvindoiv number four, which zvas 

 raised as far as possible (Fig. i). 



The wasp on entering through window number one flew 

 obliquely upwards across the beam of light from window number 

 four to the upper third of upright C. (This line of flight was 

 convex towards the east.) It then flew vertically upwards almost 

 to the ceiling then leftward about a foot (this is a little more than 

 the distance of the nest from upright B) and examined carefully 

 the moulding. Not finding the nest, it began flying first to the 

 right and then to the left in constantly elongating ellipses with 

 very short minor axes. All this time it was carefully examining 

 the moulding. Occasionally the mud-dauber would fly down- 

 ward into the beam of light and then resume its search. In its 

 lateral flights the wasp sometimes flew as far to the east as upright 

 D and to the west almost as far as upright B. At the end of three 

 minutes it had not found the nest, although under former condi- 

 tions of illumination it required only half a minute to fly from 

 window number one to the nest. 



While the zvasp zvas still searching for the nest, the top shade of 

 window number four zvas lowered and the corresponding shade of 

 windozv number three raised as far as possible. This reproduced 

 the cojiditions under zvhich the zvasp had originally worked. 



Almost immediately the wasp found the nest ! 



Experiment 2. 



The lozver shade of zvindozv number one was raised half zvay 

 and the top shade as far as possible. While the wasp was out of 

 doors, all the shades of zvindozvs number tzvo to six were lozvered 

 except the top shade of zvindozv number five, zvhich zvas raised as 

 high as possible. 



On entering, the wasp flew in a fairly direct line towards the 

 nest. When about one third of the way across the room, it re- 

 turned almost to window number one and described a circle of 

 about a foot in diameter. It then flew to the middle of the upper 



