.340 NATURE-STUDY REVIEW [11:7— Oct., 1915 



A caution with reference to comparing specimens with enlarged 

 photographs may not be out of place. The enlargement helps to 

 bring out minute characters but is apt to mislead as to general 

 a]:)pcarance unless one is careful to make allowances. A strong 

 reading glass on the sepcimens or a reducing glass on the photo- 

 graphs will help. 



The Effect of Color on the Thistle Butterfly 



An experiment by the Girls of West Vernon School, Los Angeles 



Edna Kincaid, A7 



I put some almost black caterpillars of the Thistle Butterfly 

 {Pyrameis cardui) in a pearl-grey box. In a few days they had 

 turned light grey. The spines and stripes on the caterpillar 

 matched the box exactly. It seemed too great a change to be 

 accidental. So I decided to try an experiment to see whether the 

 color of the surroundings had anything to do with the color of the 

 caterpillar. 



I lined seven boxes with pearl-grey, pink, lavender, crushed 

 apricot, blue, green, and black paper, one box with each color. I 

 then put four caterpillars in each box, putting one of the light-grey 

 caterpillars in the black box. I fed them malva, the plant on 

 which I found them. 



In two days the light-grey caterpillar had black spines and in 

 three days his body darkened. All of the caterpillars in the black 

 box turned almost black and made black chrysalids with very little 

 gold on them. 



Those in the green box turned as dark as those in the black box, 

 but the chrysalids weVe dark brown instead of black. The cater- 

 pillars raised in the blue box had brown bodies with bluish spines. 

 The chrysalids were brown with gold spots. 



The caterpillars raised in the lavendar box and those raised in the 

 pink box changed spines and stripes under the spines to nearly the 

 color of the box. These chrv^salids were light tan with many gold 

 spots. The chrysalids in the pink box were almost all gold. 



But the best match of all was in the crushed apricot box. The 

 spines and stripes of the caterpillars were a dead match for the box. 

 The chrysalids were the exact color of the box with two rows of 

 gold spots. 



The butterflies were most disappointing. We took careful 

 notice of them as they came out, and saved and mounted as many 



