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Darwin Correspondence Project

To B. D. Walsh   9 June 1868

Down. | Bromley. | Kent. S.E.

June 9. 1868

My dear Sir

I am very much obliged for your letter of May 1st, chiefly about Anthocaris.1 I had already introduced this genus into my M.S. discussion, but I shall probably be very glad to make use of the new facts which you have given me.2

It has occurred to me that you might perhaps whilst collecting, observe one subject for me without much trouble. I have lately been examining the stridulating apparatus in lamellicorns; & I am surprized to find it in a totally different position in Oryctes & Geotrupes.3 I have not yet examined enough specimens, but the organ seemed more developed in the male Oryctes than in the female.4 Now if you catch any m. & f. lamell. will you observe whether the f. can squeak or grate, or whether it does so louder than the male. If so, could you send me a m. & f. named. Does Trox exist with you? As far as I can make out with dead specimens, it grates by rubbing the spinose tibia of middle legs on the edges of the Elytra; & it seems to have no proper stridulating apparatus.5

Many thanks for your Report. I agree with your criticism on my expression; as far as I remember I used it merely because others might make a similar objection.6

This Report of yours must have cost you an immense quantity of labour. I am still at work & shall continue so for many months on the sexual differences of animals.7

With all good wishes believe me | my dear Sir | yours sincerely | Charles Darwin


See letter from B. D. Walsh, 1 May 1868. Anthocaris (a butterfly genus) is now spelled Anthocharis.
CD reported Walsh’s speculation on the colours of some Anthocharis species in Descent 1: 393–4.
See Descent 1: 378–85, especially pp. 380–1; see also letters from H. W. Bates, 20 May 1868 and 28 May 1868, letters from E. W. Janson, 25 May 1868 and 4 June 1868, and letter to H. W. Bates, 21 May [1868]. Oryctes and Geotrupes are genera of Coleoptera (families Dynastidae and Geotrupidae, respectively).
On sexual differences in the power of stridulation in Coleoptera, including Oryctes, see Descent 1: 382–4.
In Descent 1: 380, CD reported that he had ‘failed to discover the proper organs’ of stridulation in Trox sabulosus.
CD refers to Walsh’s ‘First annual report on the noxious insects of Illinois’ (Walsh 1867b). For Walsh’s criticism, see the letter from B. D. Walsh, 1 May 1868 and n. 11.
CD’s work on sexual selection in animals was published in Descent.


Thanks BDW for new facts about Anthocaris [see 6156].

Asks BDW to observe stridulation apparatus in male and female lamellicorns.

Letter details

Letter no.
Charles Robert Darwin
Benjamin Dann Walsh
Sent from
Source of text
Field Museum of Natural History, (Walsh 13) Chicago
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6236,” accessed on 21 October 2017,

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