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Darwin Correspondence Project

From Francis Darwin to Emma Darwin   [after 16 October 1868]1

Union Society, Cambridge

Dear Mama

This letter is going to be chiefly devoted to beetles & business   Will you Please send my tennis shoes   they are in the cupboard in my room, (not the spiked shoes)   also I should very much like the bottle of beetles that I left on the side board. You will be pleased to hear that the Marquis of Salisbury is going to take Holwood next winter probably in January for 6 Months

Cecil went down there to look at it & liked it very much2   I had a long work with Crotch to day at stridulation,3 & we are going to send a box of preparations to papa; from what we can make out the sexual theory seems very shaky4   we have found a new long horn which is like Prionus in having no stridular5 but it is very distinct from it in other respects  

We are still puzzled by Cychrus as the groove in the outer edge of the elytra where Crotch thought it was seems very vaguely rasped.6 He will send the sexes of two kinds of Curculionidæ, (one the Canary one).7 There is a new form of rasp in Clytus & the Lepturidæ two ridges instead of one,8 but they are in usual place on the meso thorax; also a very curious water beetle with a rasp on the elytra,9 and a beautiful Longicorn with a rasp so fine as to appear prismatic.10 all these are on card

Yr affec son | F Darwin

I hope you are better now— I have let this set on into the back of its neck to tell you I will write a less beetley letter soon

CD annotations

1.1 This … respects 2.5] crossed pencil


The date is established by Francis Darwin’s return to Trinity College, Cambridge, on 16 October 1868; he had left on 31 July 1868 (Trinity College, Cambridge, Exit and Redit books).
Holwood Park was 112 miles north of Down in the parish of Keston. Robert Arthur Talbot Gascoyne-Cecil, Viscount Cranborne, succeeded his father as third marquess of Salisbury on 12 April 1868. Francis probably also refers to the marquess’s half-brother, Sackville Arthur Cecil, who was then a student with him at Trinity College, Cambridge. The previous resident of Holwood Park, Robert Monsey Rolfe, Lord Cranworth, had died in July 1868 (ODNB).
George Robert Crotch had already corresponded with CD on stridulating beetles; see letter from G. R. Crotch, 2 October [1868] and n. 3.
After finding that stridulating organs in some Orthoptera and Homoptera differed according to sex, CD had initially expected the same to be true of Coleoptera (see Descent 1: 382). Crotch did not generally find this to be true of the specimens he sent to CD; however, he and CD later found several that differed according to sex (see ibid., pp. 383–5). See also letter to Fritz Müller, 3 June 1868, and letter from B. D. Walsh, 29 August 1868.
Prionus is a member of the Cerambycidae, the longhorn beetles. On the stridulating organs of ‘Longicornia’, see Descent 1: 380.
CD later concluded that while Cychrus emitted a sound, it did not have a true rasp (see Descent 1: 382).
See memorandum from G. R. Crotch, [after 16 October 1868]. For Crotch’s account of finding these insects, see DAR 81: 123. In Descent 1: 384, CD cited Crotch for information on stridulation in specimens of the genus Acalles (in the weevil family Curculionidae) found in the Canary Islands.
CD described parallel rasps in Descent 1: 378–9, and included an engraving of a beetle with the two rasps. The family Cerambycidae (then Lepturidae) includes Clytus.
CD described the stridulating organ on the elytra of Pelobius hermanni (now Hygrobia hermanni), a water beetle (Dytiscidae), in Descent 1: 380; see memorandum from G. R. Crotch, [after 16 October 1868] and n. 8.
Citing Hermann Landois, CD mentioned the ‘very fine ribs’ on the rasp of Cerambyx heros (now C. cerdo), a longhorn beetle, in Descent 1: 380.


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

ODNB: Oxford dictionary of national biography: from the earliest times to the year 2000. (Revised edition.) Edited by H. C. G. Matthew and Brian Harrison. 60 vols. and index. Oxford: Oxford University Press. 2004.


Has been working with G. R. Crotch on stridulation. The sexual theory seems very shaky.

Is sending preparations of beetles.

Letter details

Letter no.
Francis Darwin
Emma Wedgwood/Emma Darwin
Sent from
Union Society, Cambridge
Source of text
DAR 82: A96–7
Physical description
ALS 4pp † (by CD)

Please cite as

Darwin Correspondence Project, “Letter no. 5761,” accessed on 21 June 2024,

Also published in The Correspondence of Charles Darwin, vol. 16