ON THE LARVA OF AECTIA CAIA. 11 



'With special reference to its correlated variations in Plumage, 

 Moulting and Hybernation. 



By T. A. CHAPMAN, M. D. 



(Continued from Vol. IV., page 290). 



I have mentioned that there are at least two varieties of Forwards, 

 those that attain their full growth in the 6th skin, and those that do 

 not do so until the 7th, It so happened, that in my first brood, which was 

 apparently a very normal one, there was quite a sharp line dividing the 

 Forwards from the Normal larvte ; six larvae altogether were Forwards, 

 and I noted that these, in the 4th skin, lacked the dorsal and lateral pale 

 lines. In later broods this was not always the case, but in the 4th skin 

 the Forwards were if anything paler than the Normals at that stage, 

 and at the same time distinctly larger than Normals in 5th skin. 



In after broods there were frequently some larvee that appeared in 

 doubt as to whether they would be Forwards or Normals, assuming to 

 a slight extent the caia plumage in the 5th skin, without being larger 

 than the usual hybernating form in that skin ; others passing through 

 a normal 5th skin, nevertheless went on slowly into the 6th skin, with 

 some amount of caia plumage, without hybernating. All these com- 

 pleted their transformations without hybernation, but were always a 

 very long way behind the genuine Forwards in point of time. I have 

 since met with these forms, though very sparingly, in broods from wild 

 eggs. 



In this first normal brood the whole of the Normals acquired/?t?/(7mosa 

 plumage in the 5th skin, and there occurred only one decided but 

 also important variety, represented by four larvte which grew 

 rather larger than the others, appeared to have denser hair than the 

 usual form, had fewer of the long hairs that exist freely, though not 

 conspicuously (usually two on each tubercle), in that form, and were all 

 four of a uniform rich ruddy hue, very like the brightest form of 

 fuliginosa ; probably these, more than the normal hybernators, suggested 

 this name for the plumage of that stage. These four larvte were found 

 to differ also in another important respect from the ordinary Normals. 

 It was recognised on September 11th that they had all ceased feeding 

 and desired to hybernate, and they were accordingly placed in a cool 

 cellar. On November 23rd a number of Normals together with these 

 four special larvae were brought up into a warm room. At the end of 

 a week all the Normals had commenced to feed, but it was fourteen days 

 before these red larvae did so. It appeared therefore as if these larvae 

 were not only better nourished and more warmly clad than their 

 neighbours, but had also entered into a more profound winter sleep, 

 and it seemed natural to conclude that they were specially prepared to 

 stand a longer and more severe winter than their brethren. 



It is curious that, among the many hundreds of larvae which I 

 reared after this, I never met with one that presented jjrecisely this 

 combination of characters, not even among the progeny of these very 

 individuals. It may perhaps be going too far to suggest that, as I was 

 breeding exclusively from Forwards, the idea of a warmer climate was 

 sufficiently impressed on the race to prevent such a preparation for 

 unusual cold being made, and that the tendency to make such prepara- 



