254 Annals Entomological Society of America [Vol. IX, 



This shows that not one was holding its position with its wings 

 against the wind, but that 26 out of 30 were facing entirely or 

 partly toward the east, so the wind could not force their wings 

 open. 



Of those in the sheltered places in the low grass we have a 

 smaller number, and in the following positions : 



East, 1; North, 5; West, 1; South, 0. 



Northeast, 0; Southeast, 1; Northwest, 0; Southwest, 0. 



Here in the sheltered spots we find 5 out of 8 facing northward. 

 We could find no reason for this condition unless the moving air 

 was deflected from its course there among the lower vegetation. 



If the sleeping butterflies were disturbed early in the evening 

 they would fly to another plant; if disturbed later, just about 

 dark, they would drop helplessly to the ground or a lower leaf 

 and remain there. We routed twelve sleeping butterflies in the 

 early twilight to see in which direction they would fly in choosing 

 their new location. Every one of them flew westward, with the 

 wind. Three of them at first fluttered faintly toward the east, 

 but in a moment they righted themselves and floated westward. 



Similar observations at twilight on June 16, when an east 

 wind was blowing showed 39 out of 45 facing windward. 



On August 26, about 90 sleeping P. protodice were counted, 

 mostly upon the ragweed. The vegetation upon the field was 

 stunted and low, and the wind had a clear, open sweep across it. 

 The w4nd was from the east, and all but eight of these had their 

 heads or bodies accordingly facing eastward. 



On September 8 a strong wind was blowing from the south- 

 east. Each and every one of the 55 butterflies in- the field was 

 facing toward the wind. Each one of these was picked up and 

 thrown into the air; about half of them floated with the wind 

 and the others went with much force against the wind, but in 

 every case they soon whirled around and followed the wind. 



Seven other countings of Pieris in different places and times 

 showed the same orientation. 



The question remains: do the insects intelligently orient 

 themselves toward the direction of the wind, or does the wind, 

 when they are languid, mechanically swing them around to the 

 position of least resistance? We have not ascertained whether, 

 if the wind should change its direction during the night, it 

 would forcibly turn the butterflies about in their sleep or cause 



