Quatrefages 'Maladies Actuelles du Ver a Soie' 1859 pages 12, 214.) Analogous facts have been observed with plants: a new and beautiful white onion, imported from France, though planted close to other kinds, was alone attacked by a parasitic fungus. (21/12. 'Gardener's Chronicle' 1851 page 595.) White verbenas are especially liable to mildew. (21/13. 'Journal of Horticulture' 1862 page 476.) Near Malaga, during an early period of the vine-disease, the green sorts suffered most; "and red and black grapes, even when interwoven with the sick plants, suffered not at all." In France whole groups of varieties were comparatively free, and others, such as the Chasselas, did not afford a single fortunate exception; but I do not know whether any correlation between colour and liability to disease was here observed. (21/14. 'Gardener's Chronicle' 1852 pages 435, 691.) In a former chapter it was shown how curiously liable one variety of the strawberry is to mildew.
It is certain that insects regulate in many cases the range and even the existence of the higher animals, whilst living under their natural conditions. Under domestication light-coloured animals suffer most: in Thuringia (21/15. Bechstein 'Naturgesch. Deutschlands' 1801 b. 1 s. 310.) the inhabitants do not like grey, white, or pale cattle, because they are much more troubled by various kinds of flies than the brown, red, or black cattle. An Albino negro, it has been remarked (21/16. Prichard 'Phys. Hist. of Mankind' 1851 volume 1 page 224.), was peculiarly sensitive to the bites of insects. In the West Indies (21/17. G. Lewis 'Journal of Residence in West Indies' 'Home and Col. Library' page 100.) it is said that "the only horned cattle fit for work are those which have a good deal of black in them. The white are terribly tormented by the insects; and they are weak and sluggish in proportion to the white."
In Devonshire there is a prejudice against white pigs, because it is believed that the sun blisters them when turned out (21/18. Sidney's edition of Youatt on the 'Pig' page 24. I have given analogous facts in the case of mankind in my 'Descent of Man' 2nd edition page 195.); and I knew a man who would not keep white pigs in Kent, for the same reason. The scorching of flowers by the sun seems likewise to depend much on colour; thus, dark pelargoniums suffer most; and from various accounts it is clear that the cloth-of-gold variety will not withstand a degree of exposure to sunshine which other varieties enjoy. Another amateur asserts that not only all dark-coloured verbenas, but likewise scarlets, suffer from the sun: "the paler kinds stand better, and pale blue is perhaps the best of all." So again with the heartsease (Viola tricolor); hot weather suits the blotched sorts, whilst it destroys the beautiful markings of some other kinds. (21/19. 'Journal of Horticulture' 1862 pages 476, 498; 1865 page 460. With respect to the heartsease 'Gardener's Chronicle' 1863 page 628.) During one extremely cold season in Holland all red-flowered hyacinths were observed to be very inferior in quality. It is believed by many agriculturists that red wheat is hardier in northern climates than white wheat. (21/20. 'Des Jacinthes, de leur Culture' 1768 page 53: on wheat 'Gardener's Chronicle' 1846 page 653.)
With animals, white varieties from being conspicuous are the most liable to be attacked by beasts and birds of prey. In parts of France and Germany where hawks abound, persons are advised not to keep white pigeons; for, as Parmentier says, "it is certain that in a flock the white always first fall victims to the kite." In Belgium, where so many societies have been established for the flight of carrier-pigeons, white is the one colour which for the same reason is disliked. (20/21. W.B. Tegetmeier 'The Field' February 25, 1865. With respect to black fowls see a quotation in Thompson 'Nat. Hist. of Ireland' 1849 volume 1 page 22.) Prof. G. Jaeger (21/22. 'In Sachen Darwin's contra Wigand' 1874 page 70.) whilst fishing found four pigeons which had been killed by hawks, and all were white; on another occasion he examined the eyrie of a hawk, and the feathers of the pigeons which had been caught were all of a white or yellow colour.