of certain lepidopterous larvce and pup(e. 55 



pupae) which all feed up together, those namely which 

 will emerge the same summer, forming the heginning of 

 a second summer brood, and those which will emerge 

 next spring and belonging to the old winter brood. 



I made some observations upon the situations selected 

 for pupation, thinking that these might show some rela- 

 tion to the colours of the pupae. Of those I observed 

 11 brown pupae and 20 green were fixed to leaves ; 4 

 brown pupae and 6 green were fixed to twigs ; 10 brown 

 jDupae and 8 green were fixed to the case in which the 

 larvae had been kept (the latter having wandered from 

 their food-plants). The wandering larvae are more likely 

 to represent those which would have been normally fixed 

 to twigs. The statistics seem to point towards some 

 possible relation, but they are not convincing ; and, in 

 fact, the protection of a (yellowish) brown pupa upon a 

 leaf and of a green one upon a young twig is very con- 

 siderable. Again, some leaves bearing pupae would fall 

 off and turn brown. I hope to make further observations 

 upon this interesting question, and to investigate the 

 phenomenon in other species of Ephyridce. I should 

 have added thai I can draw no conclusions as to E. 

 omicronaria for want of sufficient material. I had 12 

 pupae (11 green and 1 brow^n), and it is probable that the 

 above conclusions have applied here, but that the brown 

 form has almost disappeared. There is not the same 

 reason for an alternate predominance of the two colours 

 at different seasons (in the pupae) because E. omicronaria 

 was, at any rate in 1883, very slightly double-brooded. 

 Only one of the 12 pupae emerged. This less marked 

 tendency to double broods may render it more likely 

 that the green forms should predominate. Thus, in E. 

 pendidaria the dimorphism is of direct value to the 

 species in two waj'S, by giving an extra chance of escap- 

 ing detection, and in the fact that the more protective 

 colour predominates at the appropriate season of the 

 year. It may be suggested that the latter gain is so 

 palpable that it is probable that the larva is progressing 

 in that direction, i. e., towards a true seasonal dimorphism. 

 But I believe that a certain proportion of brown (larvae 

 and pupae) in the summer, and a certain proportion of 

 green (pupae) in the winter, add to the safety of the 

 species ; and further, the larvae which produce the winter 

 pupa3 feed in the late summer, when green is an obvious 

 protection. Hence the predominance of brown must be 



