From J. J. Weir   [before 5] March 18681

6 Haddo Villas | Blackheath SE

March 1868

My Dear Sir

I am very much obliged to you for your Work on Domesticated Animals & propose to myself the great pleasure of thoroughly digesting it.—2

I am afraid that in my last I did not clearly shew that I understood your point on “Sexual Selection” in Lepidoptera, but I take it to be, do the females give a preference for certain males?3

It unfortunately happens that we find a most battered male in copn with a newly emerged female, and this is commonly the case with Butterflies, indeed it would appear that the female is ready to receive the male at once, but the male requires excercise particularly of the wings before it is fit for the procreative act, & this is the case even with Bombyx mori.—4

Some Butterflies when settled never open their wings, for instance Gonepteryx rhamni and the species of the genus Edusa, the underside of the former is very like a leaf and of the latter somewhat so being greenish & yellowish combined.—5

The common species of the genus Pieris and Hipparchia Ægeria very commonly fight but their colors are not bright.—6

On the other hand the bright colored Vanessæ I never saw in copn.—7

Nearly the whole of the Noctuæ8 are dull colored insects & fly by night, but the Genus Triphæna (Yellow Underwings) fly by day, the ♂ & ♀ are alike & the bright yellow underwing is in my opinion an advantage in the struggle for existence, thus, I placed a vigorous specimen of Tria pronuba9 in my aviary, it was at once attacked by a robin, in endeavouring to escape it shewed the yellow color, this caught the bird’s attention, and of course when seized a little piece was bitten out & the insect escaped, this was repeated about 50 times before the capture was made & the insect swallowed. I feel confident that if the struggle had taken place in nature the moth would certainly have escaped.—

Again I allowed Triphæna fimbria to escape just in front of a swallow, the bird at once dashed in pursuit but from its inability to seize the insect, it effected its escape and flew off unscathed, at a great height10

I may mention here a curious fact that has been known to me nearly a quarter of a century.—

The late Edward Doubleday of the British Museum once shewed me a Lepidopteran ♂ without wings, I at once exclaimed it ought to have come from Kirguelens Land, & curiously enough it did11

I presume that on that island no insectivorous bird exists & it is also probably a very windy place, so that wings being not only useless, but injurious have become obsolete.

I have never heard of the insect since his death but should suppose it is probably in the British Museum.—

I have this day secured a very dull colored Bullfinch, nearly black, for experiment & propose the highten the color of a chaffinch by staining the breast with roseine,12 leaving my other chaffinch ♂ the ordinary dull color of a caged bird of the species.—

Bates & Moore are coming to dine with me today   I will have some conversation with them & write further in a few days13

I am | My Dear Sir | Yours very faithfully | J Jenner Weir

C Darwin Esqr.—

CD annotations

1.1 I am … it.— 1.2] crossed pencil
2.1 I am … copn.— 6.1] crossed blue crayon
4.2 Edusa,] ‘Colias’14 added pencil
7.1 Nearly … century.— 9.2] crossed ink
7.1 Nearly … escaped.— 7.9] ‘It is always good to learn how ignorant we men are of use of Parts | Like Wallace Big wings of Lepidoptera’15 added ink
10.1 The late … few days 14.2] crossed pencil
Top of letter: ‘B’ ink; ‘B’ blue crayon, circled blue crayon
1
The date is established by the relationship between this letter and the letter to J. J. Weir, [6 March 1868].
2
Weir’s name appears on CD’s presentation list for the second printing of Variation (see Correspondence vol. 16, Appendix IV).
4
In his letter of [before 3] March 1868, Weir had written that male silk moths were eager for copulation as soon as their wings expanded.
5
The underside of the wings of Gonepteryx rhamni (the brimstone butterfly) is yellowish in males and pale green in females. In Colias edusa (the clouded yellow butterfly; now C. croceus) the underside of the wing is mostly green with a splash of yellow near the top (see Moths and butterflies of Great Britain and Ireland, vol. 7, pt. 1).
6
Butterflies of the genus Pieris (family Pieridae) are mostly white. Hipparchia aegeria is a synonym of Pararge aegeria (the speckled wood), family Nymphalidae, subfamily Satyridae), which is brownish (on the use of ‘Hipparchia’ as a general term for satyrid species, see Emmet 1991, p. 30).
7
Vanessa, a genus in the family Nymphalidae, has bright coloured wings, with cryptic underwings resembling tree bark.
8
Noctuae was the name of a group of moth families roughly equivalent to the present superfamily Noctuoidea.
9
Triphaena pronuba, the large yellow underwing moth, is now Noctua pronuba (Moths and butterflies of Great Britain and Ireland, vol. 9).
10
Triphaena fimbria, the broad-bordered yellow underwing moth, is now Noctua fimbriata (Moths and butterflies of Great Britain and Ireland, vol. 9). CD cited Weir’s information on both species of Triphaena in Descent 1: 395.
11
Doubleday was an assistant in the zoological department of the British Museum from 1841 to 1849 and had been responsible for building a large collection of Lepidoptera (ODNB). Kerguelen’s Land is a subantarctic island group in the South Indian Ocean, about 3300 miles south-east of the southern tip of Africa (Columbia gazetteer of the world).
12
Roseine: one of the red salts of rosaniline, a dye (OED). See letter to J. J. Weir, 27 February [1868].
13
Henry Walter Bates and Frederic Moore were both entomologists.
14
CD added the genus name, as Weir had only given the species epithet for Colias edusa (see n. 5, above).

Please cite as “DCP-LETT-5985,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5985