154 THE ENTOMOLOGIST. 



on the contrary, cocoons spun in a tin box, in which a consider- 

 able amount of moisture was caused by the food-plant placed 

 with the larvfe, were just as invariably of a bright yellow colour. 

 To test the effect of damp, I immersed two of the white cocoons, 

 which had been spun in chip boxes, in water, and was surprised 

 at their rapid change to yellow.* 



I have noticed a somewhat similar change in the cocoons 

 constructed by ichneumons of the genus Phytodietus. These 

 parasites are frequently met with, preying, as they do, on some 

 of our commonest species of Tortrices ; the cocoons they make 

 are thin, papyraceous, and pure white in colour, but if dipped 

 in water at once turn to a deep brown ; indeed, a very slight 

 degree of moisture is sufficient to cause the change, so that it is 

 very rarely a cocoon is found in its natural position, between 

 the leaves spun together by the host, which is anything but 

 brown in colour. 



That all pale cocoons do not turn colour when subjected to 

 moisture is well known. For instance, the white cocoons often 

 constructed by the silkworm Bomhyx mori suffer no change when 

 thoroughly soaked in water, and the cocoons of SinKsthisfahri- 

 ciawi furnish another common example. 



The subterranean cocoons made by the Braconids Meteorns 

 deceptor, M. chloropthalmus, and Zele ivfamator are pure white, 

 and remain so, no matter how damp is the earth surrounding 

 them. Many of the genus Apanletes also spin white silk, which 

 is not affected, though I have noticed the curious ball of silk in 

 which the cocoons of A. co)igestusa,Ye enclosed to take a yellowish 

 tint when exposed to the weather. 



It seems only reasonable to conclude that the viscous liquid 



from which silk is spun varies in its chemical constitution, and 



it is to be hoped that some entomologist with a knowledge of 



chemistry may take the matter up, and so throw light on a most 



interesting subject. 



Mayfielcl, Lensfield Eoad, 

 Cambridge. 



LIST OF BUTTERFLIES TAKEN IN THE NEIGHBOUR- 

 HOOD OF LOS ANGELES, CALIFORNIA. 



By Margaret E. Fountaine, F.E.S. 



Thesk butterflies were all taken from the beginning of 

 February to the middle of April, and include the following : 



1. Papilio zelicaon, Boisd. First seen end of January. Very 

 common the beginning of March, but only so especially in one 



* I can confirm Mr. Lyle's observations of the cocoon colour of Plusia moneta. 

 Cocoons found in situ on food-plant in garden, yellow ; spun up in small dry 

 breeding cage, white. — H. R.-B 



