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Darwin Correspondence Project

From George Fraser   13 April 1871

169 Camden Road | London N.W.

13 April 1871.

Chas. Darwin Esqr.

Dear Sir,

The Ghost Moth.

On thinking over the fact mentioned at page 402 in the first volume of “The Descent of Man”, that “in the Shetland Islands males (of H. humuli) are frequently found which closely resemble the females”1—which fact I can corroborate, as I have seen male specimens thus varied in collections made at Peterhead2—it occurs to me that this smaller variation in the case of the male moth may arise as follows: The twilight in those northern regions at the season of the year when H. humuli abounds is so different from our southern twilight that one might say there is no dusk in the north at that time; and thus the mode of sexual selection which I supposed to influence the appearance of the male moth in my letter to you of yesterday would not come into operation there.— But would not this be in truth a confirmation of the theory I ventured to lay before you?—3

Yours most respectfully | George Fraser

CD annotations

Top of letter: ‘Fraser’ red crayon


Descent 1: 402–3. Hepialus humuli is the ghost moth.
Peterhead is in Aberdeenshire, Scotland.
See letter from George Fraser, 12 April 1871. CD cited these comments in Descent 2d ed., p. 316 n. 21.


Descent 2d ed.: The descent of man, and selection in relation to sex. By Charles Darwin. 2d edition. London: John Murray. 1874.

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


Corroborates and offers explanation of fact that male ghost-moths (Hepialis humuli) closely resemble females. [See Descent 1: 402.]

Letter details

Letter no.
George Fraser
Charles Robert Darwin
Sent from
London, Camden Rd, 169
Source of text
DAR 89: 103
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 7681,” accessed on 4 July 2020,

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