REACTIONS OF ARTHROPODS TO LIGHTS 



481 



all outward appearances unaffected by the red (fig. 14). These 

 reactions of the larvae to pairs including yellow Hght demon- 

 strate that yellow is more stimulating to the larvae than red 

 but less than either blue or green. 



A study of the records made by the larvae when under the 

 influence of green in opposition to blue, yellow or red (figs. 15 to 



Figs. 9 to 1-4 Paths traced by Calliphora larvae, in dilute solutions of methyl- 

 ene blue, in response to balanced pairs of monochromatic lights of the following 

 pairs: 



Fig. 9 Red-blue Fig. 12 Yellow-blue 



Fig. 10 Red-green Fig. 13 Yellow-green 



Fig. 11 Red-yellow Fig. 14 Yellow-red 



17) show that green not excepting blue is the most powerful as 

 an agent for orientation. As might be predicted from the pre- 

 vious experiments the course of a larva started in the yellow or 

 red is reversed when the green is turned on. The course of the 

 same larva oriented in the green is not effected by the red and 



