AND OF PRODUCTS OF METABOLISM. 289 



when fed on deadly nightshade the brown markings of 

 the upper wings often coalesce and the white vanishes; 

 in like manner the blue markings on the lower wings 

 fuse together and displace the orange-yellow ground 

 colour." 



A careful series of observations upon various moths, 

 extending over some ten years, has been made by Greg- 

 son, t His results may be tabulated as follows: 



Pygcera bucephala (Buff Tip) is finer and darker when fed upon 



sycamore. 

 Xylophasia polyodon (Dark Arches) is dark, sometimes black, when 



fed upon heather. 



Hadena adusta (Dark Brocade) is darker when fed upon heath. 

 Acronycta menanthydis (Light Knot-Grass) when fed on sallow, often 



produces var. A. salycis; fed on heath, produces light 



specimens. 

 Hybernia defoliaria (Mottled Umber) is beautifully marked when fed 



upon birch; but on elm gives dull-coloured forms, almost 



without markings. 

 Eupithecia venosaria (Netted Pug) fed on inflated catchfly is almost 



white; on shore catchfly is much larger and almost lead 



colour. 

 Noctua j 'estiva (Engrailed Clay) fed on thorn is rich red and well 



marked: on grasses is light yellowish, and rarely well 



marked. 

 Noctua triangulum (Double-Square Spot) fed on thorn is dark: fed 



on low plants is light. 



Abraxas grossulariata (Magpie) fed on red currant is light; on black- 

 thorn is darker; on bullace or wild plum is darker still, 



the white sometimes becoming yellow. 



The following case, recorded by the late Mr. New- 

 man^ is of especial interest in that it occurred under 

 natural conditions. The larva of V. polychloros (Large 



*IMd., p. 151. 



fThe Zoologist, p. 7903, 1862. 



\ The Entomologist, vi. p. 88, 1873. 



