It has long been known that caterpillars which feed on flowers or on plants of variously-coloured foliage, in some cases partake of the colour of their food. See, for instance, Dr. L. Möller’s memoir, “Die Abhängigkeit der Inseckten von ihrer Umgebung,” 1867, and B. D. Walsh “On Phytophagic Varieties and Phytophagic Species,” Proc. Ent. Soc. Philadelph., vol. iii., p. 403. In 1865 Mr. R. McLachlan published a paper entitled “Observations on some remarkable varieties of _Sterrha Sacraria_, Linn., with general notes on variation in Lepidoptera” (Trans. Ent. Soc. 1865, p. 453), in which he gave many illustrations of this phenomenon. The larva of _Heliothis Peltiger_, according to Mr. Reading’s description (Newman’s “British Moths,” p. 438), is another case in point. In 1874 a number of instances were published by Mr. Thomas G. Gentry in a paper entitled “Remarkable Variations in Coloration, Ornamentation, &c., of certain Crepuscular and Nocturnal Lepidopterous Larvæ” (“Canadian Entomologist,” vol. vi., p. 85. See also W. H. Edwards’ description of the summer and autumnal larvæ of _Lycæna Pseudargiolus_; _Ibid._, vol. x., pp. 12, 13). The caterpillars of the _Sphingidæ_ appear also in some cases to vary in a manner very suggestive of phytophagic influences. The observations upon _S. Ocellatus_ recorded in the previous note (p. 241) may perhaps be interpreted in this sense. In order to get experimental evidence upon this subject, I may add that Mr. E. Boscher was good enough at my request to repeat his observations, and conduct some breeding experiments during the present year (1880). In the same locality as that previously mentioned, seven larvæ were found feeding on _Salix viminalis_, all of which were the bright green spotted variety; and in the same osier-bed six more were found on another species of _Salix_, two of these being the bluish-green variety, and the other four the bright green form. Unless we have here a local race, these observations, in connection with those of last year, tend to show that the light green form is associated with _Salix viminalis_. When found in the natural state feeding on apple, the caterpillar of this species is generally, perhaps invariably, the bluish-green form. In order to try the effect of breeding the larvæ _ab ovo_ on distinct food-plants, a large number of eggs laid by a female _Ocellatus_ in July were divided into three batches, one being supplied with _Salix triandra_, another with _S. viminalis_, and the third lot with apple. The experiment unfortunately failed in great part, owing to most of the larvæ dying off, three from the third lot only surviving; but these were all of the bluish-green form, which colour was shown by all the caterpillars of this batch from their earliest stage. The observation is thus so far successful, as it goes to support the view that the variety mentioned is associated with apple (and _S. triandra?_) My friend Mr. W. J. Argent informs me that he had a number of specimens