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Darwin Correspondence Project

To Benjamin Dann Walsh   3 April [1869]1

Down. | Beckenham | Kent. S.E.

April 3d.

My dear Sir

I have received your kind letter of March 12th & the 3 numbers of the Amer. Entomologist.—2

I am very glad that you have proved your case about the dimorphism of the Cynips.—3 I will send by this Post the specimens to Fred. Smith of Brit. Museum,4 either for his private or the public collection as he may think best.—

What an admirable Journal your new one is: I have read two numbers, but not as yet that on Wasps,5 but I shall begin it this evening.— Nothing in my opinion can be better than the two articles on Galls & the Cicadas. That is a most perplexing case about the 2 forms of the Cicadas.—6 The galls interest me much, not so much as galls, but as a proof what organic changes extraneous matter can cause.—7 There are numbers of curious facts, for example the sterility of the Hateful Grasshopper.—8

I will not so much trespass on your kindness as to accept the rare back numbers; but if you publish anything which you think would interest me (& you can judge almost as well as I can myself) I shd. be grateful for an odd number.—9

My dear Sir | Yours sincerely | Ch. Darwin

P.S. I have just finished your Wasp paper—10 it is capital   very interesting & very amusing.—


The year is established by the publication date of the American Entomologist articles sent by Walsh (see n. 2, below).
Walsh’s letter has not been found. CD refers to issues 4, 6, and 7 of the first volume of the American Entomologist, dated December 1868, February 1869, and March 1869 respectively. The issues are in the Darwin Pamphlet Collection–CUL; four articles by Walsh and Charles Valentine Riley (B. D. Walsh and Riley 1868a–b and 1869a–b) are annotated (see nn.3, 5, 6, and 8, below).
Experimental proof that the gall wasp Cynips quercus aciculata, hitherto regarded as a distinct species, was one of the two female forms of C. q. spongifica was presented in B. D. Walsh and Riley 1869a, p. 103; Walsh had explained the experiment in his letter to CD of 12 November 1865 (Correspondence vol. 13). For Walsh’s initial speculation on the subject, see B. D. Walsh 1864, pp. 447–8, and Correspondence vol. 12.
Frederick Smith was an entomologist in the British Museum.
Walsh and Riley started the American Entomologist in 1868 (see Correspondence vol. 16, letter from B. D. Walsh, 29 August 1868). The article on wasps is B. D. Walsh and Riley 1869b.
In ‘The periodical cicada’ (B. D. Walsh and Riley 1868a), the authors described Cicada septemdecim (now Magicicada septendecim), which emerged every seventeen years, and a cognate species, which emerged every thirteen years; see also Correspondence vol. 16, letter from B. D. Walsh, 29 August 1868 and n. 17, and letter to B. D. Walsh, 31 October 1868.
CD had cited Walsh’s earlier paper on galls (B. D. Walsh 1866) in Variation 2: 282–5.
In ‘The hateful or Colorado grasshopper’, Walsh and Riley discussed the sterility of the grasshoppers born on the plains; the fertile grasshoppers migrating from mountain canyons were destructive but their young ate little and did not breed ([B. D. Walsh and Riley] 1868b). The species, Melanopus spretus, also known as the Rocky Mountain locust, is now extinct (Lockwood 2004).
Though no further correspondence with Walsh has been found, issues of the American Entomologist for April, September, and October 1869 are in the Darwin Archive–CUL.
See n. 5, above.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 26 vols to date. Cambridge: Cambridge University Press. 1985–.

Lockwood, Jeffrey Alan. 2004. Locust: the devastating rise and mysterious disappearance of the insect that shaped the American frontier. New York: Basic Books.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Glad BDW has proved his case on dimorphism of Cynips.

Interested in galls

and BDW’s Cicada articles [Proc. Entomol. Soc. Philadelphia (1864)].

Letter details

Letter no.
Charles Robert Darwin
Benjamin Dann Walsh
Sent from
London | Ap 5 | 69
Source of text
Field Museum of Natural History, Chicago (Walsh 17)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5482,” accessed on 25 January 2020,

Also published in The Correspondence of Charles Darwin, vol. 17