hetvjeen lepidoptcroios larvm and their siorroundings. 361 



Jime 26th. The 2 dark larvae mature and removed. 

 The 5th larva had now became a typical and distinct 

 bright green form, the brown dorsal line having almost 

 disappeared. 



July 2nd. The green larva mature and removed. 



CONCLUSIONS. 



This is a deeply interesting little set, showing the effect 

 of the dark surroundings persisting unaltered in the 2 

 larvae which were first to pupate, the green environment 

 producing some effect in the greyness overspreading the 

 next 2, and predominating altogether in the last. 



B. A. betularia. 



May 20th. The 51 hetularia larvae remaining in the stock, 

 with green leaves and shoots of Popmlus nigra, Avere care- 

 fully examined. Two larvae had just entered the 3rd stage, 

 having changed the 2nd skin, 5 were small in the 2nd 

 stage, while all the rest were changing the 2nd skin, and 

 thus at the end of the 2nd stage. Twenty of these latter 

 were transferred to a cylinder (B'^j with an abundance of 

 black twigs of the Turkish oak, while the remainder were 

 put back into the green environment. From this date to 

 the 25th all the larvae were fed on Balsam Poplar. 



May 2oth. Thirty larvae counted at this date. Of these, 

 15 changing the 3rd skin were transferred to a cylinder 

 (B^) with black twigs. The remaining larvae were smaller, 

 but even in the 3rd stage a small proportion of green in- 

 dividuals had begun to appear among the brown. All 

 the larvae were fed on Popuhis nigra from this date 

 (May 25th) onwards. 



May 29th. The 15 larvae remaining in the green environ- 

 ments were mostly at the end of the 3rd stage and many 

 were changing the 8rd skin. They were mostly light 

 brown but some were green. 



June 2nd. Six larva3 had reached the end of the 4th 

 stage, although they were not changing their skins. Of 

 these 5 were green with slight traces of brown, while the 

 6th, although green, retained a larger amount of the darker 

 shade. Six larvae were smaller, having reached various 

 points in the 4th stage. Of these 2 were green with 

 slight traces of brown, while four were brownish-green or 

 lifrht sfreenish-brown. Three larva:- were still in the 3rd 



