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Darwin Correspondence Project

From A. G. Butler   26 May 1871

17 Oxford Road, Ealing

26th. May 1871.

Dear Sir

I have been reading your Descent of Man & it has stirred me up to put together a few facts which I think may possibly prove useful to you—

The other day I was much interested in watching a male Anthocharis cardamines which as you know usually settles upon the wild carrot flowers: I was in a lane near a very attractive garden, no wild carrot grew within about half a mile of the spot, but at about 200 yards from the garden was a little patch of shepherds purse in flower & the orange-tip, every time he wished to settle left the garden & flew up the lane until he arrived at this patch where he alighted under my very nose & closed his wings, the shepherds purse concealed him almost as effectually as the wild-carrot; here I think was an amount of reasoning equal to that exhibited by Kallima when settling on its dead leaves—1

Some years ago I wished to procure some fresh ♂ Pieris brassicæ2 for my cabinet & I obtained them by means of a living female attached to a piece of thread so as to allow her to rise a short distance in the air.

Smith & Abbot, remarking on the resemblance borne by Callidryas Eubule to its foodplant, suggest that the female is led to deposit its eggs upon the plant which reminds it of its mate.3

You observe in ‘Sexual Selection’ that the sexes of the Hipparchiæ & Danaidæ do not differ, this is not strictly correct;4 Epinephele Janira differs so much in the sexes that Linnæus described it & its female as distinct, though consecutive, species; the male Danaids are (I think without exception) more likely to be rapid flyers than the females their frontwings being longer & more pointed.5

I have recently published a note in P.Z.S. on the frequent abnormalities in neuration of Acræa andromacha,6 I think we may see here how new genera take their rise amongst butterflies.

Whilst breeding Lepidoptera I have been struck with the much greater number of males in the commoner species & I think the excessive number of this sex is the cause of the ubiquity of such species   there can be no mistake about this in Orgyia antiqua, as the sex can be readily seen in the larval condition, the tufts of hair on the back being yellow in the ♂ & brown in the female.7

I can hardly think that the jaws of Lucanus cervus were developed solely (if at all) for the sake of fighting other males, as the females certainly hurt a great deal more than the males, as I know from personal experience, & I think we should find that the longer the jaws were the less powerful they would be; I think perhaps the variability in these jaws may be caused by a constant struggle between natural selection & sexual selection; the former demanding short jaws, the latter long.8

I don’t know if you have ever noticed the great difference in the sexes of the Crustacean genus Huenia (Decapods),9 I was much astonished when I suddenly dropped upon them today, the differences are about as under


Hoping that this long rigmarole will not worry you

Believe me to be | yours very sincerely | A G Butler.

Ch. Darwin Esqre. | &c &c &c

CD annotations

1.1 I have … to you— 1.2] crossed pencil
1.1 I have … spot, 2.3] ‘Case of concealment— not worth giving’ added blue crayon
3.1 procure … the air. 3.3] scored blue crayon; reverse question mark added blue crayon
4.1 Smith … mate. 4.3] crossed pencil
5.1 You … species; 5.3] double scored blue crayon
6.1 I have … butterflies. 6.3] scored blue crayon
7.4 as the … female. 7.5] double scored blue crayon, pencil; ‘Looks to like correlation— important if mature sexes differ.’ added pencil
8.2 the females … experience, 8.3] triple scored blue crayon
Top of letter: ‘(1)’ red crayon


Anthocharis cardamines is the orange-tip butterfly. Shepherd’s purse is Capsella bursa-pastoris. CD described Kallima inachus (the orange oakleaf or dead-leaf butterfly), which with its wings closed resembles a dry leaf, in Descent 1: 392.
Pieris brassicae is the large white or cabbage butterfly.
Callidryas eubule is now Phoebis sennae, the cloudless sulphur butterfly. In J. E. Smith and Abbot 1797, Tab. V and p. 9, the species is given as ‘Papilio Eubule, the American brimstone butterfly’; it is shown with Cassia chamaecrista, dwarf cassia.
See Descent 1: 387.
Epinephile janira is now Maniola jurtina (the meadowbrown butterfly); the species shows marked sexual dimorphism. Butler refers to the two species, Papilio janira and P. jurtina, described by Carolus Linnaeus (see Linnaeus 1758–9, p. 475). Danaidae is now Danainae, a subfamily within the Nymphalidae.
The reference is to Butler 1870, published in the Proceedings of the Zoological Society of London. Acraea andromacha (family Nymphalidae) is the glasswing butterfly.
Orgyia antiqua is the vapourer moth.
In Descent 1: 375–6, CD described the large mandibles of male stag beetles (Lucanus cervus) as ‘well adapted for fighting’.
Huenia is a genus of spider crabs in the family Epialtidae.


Butler, Arthur Gardiner. 1870. Note on abnormalities in the neuration of the hind wings in Acræa andromacha. [Read 15 November 1870.] Proceedings of the Zoological Society of London (1870): 777–78.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Linnaeus, Carolus (Carl von Linné). 1758–9. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. 10th edition. 2 vols. Stockholm: Laurentius Salvius.


Several observations on protective coloration and sexual selection.

Letter details

Letter no.
Arthur Gardiner Butler
Charles Robert Darwin
Sent from
Source of text
DAR 89: 104–7
Physical description
ALS 7pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7770,” accessed on 17 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 19