REACTIONS TO LIGHT IN VANESSA ANTIOPA 



379 



tions of three other insects showing similar behavior are pre- 

 sented in figures 5, 6 and 7. 



The results presented in these figures as well as in the preced- 

 ing ones seem to show that butterflies with but one functional 

 eye improve in the accuracy of orientation with experience. This 

 conclusion and others are strongly supported by the results 



Fig. 5 Reproduction of 15 successive trails made by butterfly 7/29-c (right eye 

 blackened), a and h, limits of horizontal beam of light; 1-15, paths made in 

 successive trials; small arrows, direction of movement of animal; large arrows, 

 direction of rays of light; illumination at x, 4892 mc; at y, 544 mc. Note that 

 this insect made three circus movements in the first four trials, while in the next 

 eleven trials it made none. 



obtained in all of the tests made. These are briefly summarized 

 in table 1. 



This table will be clearer if a brief explanation of some of the 

 data is given. In the columns headed 'Direction turned' is 

 stated the direction toward which the butterflies turned immedi- 

 ately after they were placed in the beam. The average angle 

 of deflection was ascertained in the following way. The angle 



