My dear Sir,

With this you will receive a few specimens of Tortrix of which I beg your acceptance— they will illustrate the extraordinary variation of markings in two or three species—¹

No 1. Peronea Hastiana. (Tortrix Hastiana of Linné)—the description in the Fauna Suecica applies to the variety marked thus + —and the specimen is still in the Cabinet—² This species feeds in the larva state upon the sallow and most of the varieties may be obtained from one brood of larvae—but they seem almost endless and have been considered by most of the older writers as distinct species— — I believe I was the first person in this country who felt convinced that the host of nominal species of these Buttons” as they are called, would sink into two—Hastiana and Cristana—and this ⁠⟨⁠  ⁠⟩⁠ by everyone—³

No. 2. Peronea cristana— this species is equally as variable as the last but all the varieties have a raised tuft or button on the upper varying much in size and colour—

No 3. Pœdisca sordidana— this species varies very much as you will see by the two specimens sent—

In every family of Lepidoptera there seem to be two or three species extremely prone to vary—and it is certain that in some localities they vary more than they do in others. In rearing Lepidoptera from the eggs I have frequently found that if you have a brood from a typical female of a varying species the moths will all be like the parents—

Some years ago I made some experiments with the varieties of Harpalyce Russata— Haworth & Stephens described several of these varieties as distinct species—⁴ I felt convinced that they were all one and to prove it I caught several fem⁠⟨⁠ales⁠⟩⁠ and obtained a numb⁠⟨⁠er⁠⟩⁠ of eggs— I had bro⁠⟨⁠ods⁠⟩⁠ from three typica⁠⟨⁠l⁠⟩⁠ ⁠⟨⁠  ⁠⟩⁠ of Haworth and when the moths appeared they were all exactly alike— after this I caught a female of the yellow-banded variety—the Comma-notata of Haworth—and from the eggs of this female I reared all the varieties— With the central fascia yellow—white—black—and all intermediate shades constituting the Centum-notata, Comma-notata, perfuscata &c of Stephens— —

It is singular that some species should vary so much while others closely allied should scarcely ever vary at all— species too, really distinct—often approach so closely as to be separated with difficulty in the perfect state— for instance Acronycta Psi, tridens and Cuspis— yet the larvae of these three species are totally different from each other—

Locality seems to affect the shade of colour of many species— Scotch specimens of Lepidoptera are generally much darker than those of the south of England— this is particularly the case with Aplecta occulta, Hadena adusta, Xylophasia polyodon, and Aplecta tructa.

I hope you will write again if you want any other information that it is in my power to give⁵ and with best wishes believe me | My dear Sir | Yours most sincerely | Henry Doubleday Charles Darwin Esq

I do not want the box returned as it is of no value | H Dy