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Darwin Correspondence Project

From H. W. Bates   21 February 1868

Royal Geographical Society | 15, Whitehall Place, S.W.

Feb 21 1868

My dear Mr Darwin

Mr Westwood very unfortunately tried to introduce names for the families of Leaping Orthoptera, different from those used by several authors of Monographs.1


Achetidæ = Achetidæ of majority of authors but
Gryllidæ! of some.
Gryllidæ = Locustidæ of majority
Locustidæ = Acridiidæ—do—

You might use English names for first & last—“Crickets” & “Grass hoppers”—but the second have no English name.2

In “Amazons vol I. 250; I aimed at showing there was a gradation of perfection in the stridulating organs at base of wing-cases.3 What I stated about Crickets was the result of visits to Baker’s ovens at the time,4 dissection of fresh specimens & examination of many foreign achetidæ; and on looking at a few species I have at hand I still say that the edges of base of wing cases of Achetidæ are not forced out of symmetry; i.e not produced into lobes of different shapes & widely different structure,—as they are in Locustidæ, where also the organs advance gradually from genus to genus (speaking generally) to a high degree of elaboration.

On looking at Westwood’s figures of Achetidæ, quoted in your letter, I find he does not figure two wing-cases of a male but one of a male & one of a female.5

It is however probable that in some true crickets (achetidæ) there may be some differences in the two wing-cases; it would be advisable therefore to avoid making too sweeping an assertion about their symmetry throughout the family;6 this is not essential to the argument, which is that there is a gradation in asymmetry & a step by step advance to a wonderful musical instrument.

Want of symmetry in the same pair of wings of insects is an exceedingly rare phenomenon and how it could first occur by variation in these orthoptera, so as to give Nature the first chance of a musical instrument, is a curious question. I think it occurred through the overlapping of the inner edges of base of wing-cases, caused simply by the shape of the wings & body, without any reference to a musical instrument being afterwards elaborated.

Yours sincerely | H W Bates

CD annotations

2.2 Achetidæ] ‘Crickets’ added blue crayon; ‘Both wings rasped’ added pencil
2.5 Locustidæ] ‘Grasshoppers’ added blue crayon; ‘(Femur)’ added ink
5.1 On looking … female. 5.2] scored red crayon
6.1 It is … wing-cases; 6.2] ‘See list of Westwood’ added pencil


CD had asked about family names in John Obadiah Westwood’s Introduction to the classification of insects (Westwood 1839–40). See letter to H. W. Bates, 19 February [1868].
In his discussion of Orthoptera in Descent 1: 352–61, CD used the family names Achetidae, Locustidae, and Acridiidae throughout; he remarked that there was no common English name associated with the Locustidae (ibid., p. 352). For more on the taxonomy of Orthoptera, see the letter to H. W. Bates, 19 February [1868], n. 3.
See Bates 1863, 1: 250–3. CD scored passages in Bates’s discussion of the comparative structure of the wing cases in different families of Orthoptera (see Marginalia 1: 35). CD referred to Bates’s discussion in Descent 1: 353 n. 29.
Bates probably refers to George Baker, a specialist in Lepidoptera who bred insects and supplied specimens to collectors (Entomologist 46 (1913): 120).
CD described both wing cases in the Achetidae as having ‘the same structure and the same function’ (Descent 1: 353, 355).


Bates, Henry Walter. 1863. The naturalist on the River Amazons. A record of adventures, habits of animals, sketches of Brazilian and Indian life, and aspects of nature under the equator, during eleven years of travel. 2 vols. London: John Murray.

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

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

Westwood, John Obadiah. 1839–40. An introduction to the modern classification of insects; founded on the natural habits and corresponding organisation of the different families. 2 vols. London: Longman, Orme, Brown, Green, and Longman.


Comments on J. O. Westwood’s entomological nomenclature.

Discusses the organs for stridulation in Orthoptera [see Descent 1: 352ff].

Letter details

Letter no.
Henry Walter Bates
Charles Robert Darwin
Sent from
R. Geogr. Soc.
Source of text
DAR 82: A32–3
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5909,” accessed on 28 January 2022,

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