90 Journal New York Entomological Society. [Vol. xm. 



opening the bag I found one which had grown larger, but still re- 

 mained white, certainly not yellow. 



August 20 I again opened the bag ; the largest one was greenish 

 white on the cephalothorax and legs, but the abdomen was pale yel- 

 lowish ; the smaller one had become yellowish all over, the body and 

 legs distinctly yellowish, and the abdomen a little deeper yellow. 

 This seemed a good test, and so far as a single experiment indicates, 

 it shows that the change of color does occur in middle life, or when 

 the spider is about half grown. The change evidently takes place in 

 the pigment of the integument, as the result of exposure to yellow 

 light reflected from the yellow flowers. In this way the spiders be- 

 come adapted to their yellow environment. 



The change requires certainly more than two or three days, i. e. , 

 about a week or ten days. Thus on the 23d of August I placed a single 

 white M. vatia found the day previous on the golden rod, in a bag 

 containing a full head of yellow golden rods, and on opening it three 

 days after (the 26th) it had not changed. On September 3 I opened 

 the same bag and found the cast skin of the same white spider, the 

 spider was not of full size, it was not distinctly yellow, being still whit- 

 ish, with a greenish abdomen but slightly tinged with yellow. There 

 was a dark green line on each side of the cephalothorax. Unfortu- 

 nately the bag was not again opened, as I failed to return to Merepoint 

 and was thus prevented from afterwards examining the specimen. 



Previously Published Notes on Change of Color 

 in Flower Spiders. 



The foregoing observations were made and written out either 

 before meeting with the published observations of others, or if read in 

 former years they had been forgotten. 



Besides the note published by Mr. Angus, Mrs. Mary Treat * states 

 that Thomisus celer which lives in the heart of roses is nearly of the 

 same shade of color as the red flower, and that when the spider is 

 " waiting for prey she cuddles down in the center of the flower and 

 erects her legs, when it is almost impossible to distinguish them from 

 the imperfect scattering stamens." Mrs. Treat also observed a spider 

 catch a butterfly, and adds that she had often noticed the remains of 

 of night-flying moths scattered near her, which she had evidently 

 captured during the night. 



* My garden pets, Boston, 1887, p. 12. 



