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Darwin Correspondence Project

From Frederick Smith   14 September 1869

Brit. Museum.

14 Septr. 1869.

My dear Sir

I regret that I am not prepared to decide as to whether the sexes stridulate in Mutilla   I can only affirm that the female does so—and that so sharply as to attract your notice immediately—1 I have taken more specimens of the Male than the female but have not certainly noticed in the former sex.— One of the musicians that I have heard is Trox sabulosus— this insect I once observed on the wing— it settled in the grass within a yard of me—and on doing so I was attracted by the shrill tone it produced— I caught it in my hand and so loud was the squeak-like noise that a gamekeeper who was standing by asked if I had caught a mouse—2 All the species of Necrophorus stridulate loudly3—but the most amusing performance is that the little weevil Acalles roboris—4 it is about this size.


You will recollect Mr Wollastons paper in the Zoologist on the Musical Curculio—that he found I think in Madeira— this was a Sp. of Acalles5   Wollaston wrote to me when I was at Deal where the Acalles roboris is plentiful asking me to observe whether this little sp.c was musical— I obtained about 20— I had to place them in a small pill box—then shake them up—and on applying the box to my ear—their music was distinctly audible— I tried—various experiments placing 6. 4. 3. 2. 1 in the box— the single beetle was very difficult to hear— the tone was shrill but very low but I did hear it— the tone was produced by rubbing the abdomen against the elytra—there being a very smooth space on which -it operated— Wollaston has described it in his paper

I shall probably see you soon when I might be able to say more— next week I shall I expect be in the Isle of Wight

Yours very truly | Fredk. Smith

CD annotations

1.1 I regret … sex.— 1.4] crossed pencil
1.5 Trox sabulosus] ‘Troxadded pencil
1.7 I caught … gamekeeper 1.8] scored blue crayon
1.8 All … roboris— 1.10] crossed pencil
1.15 I tried … Wight 2.2] crossed pencil
Top of letter: ‘Get reference to Wollastons Paper.— | Sexes of Mutilla to examine—6 | How are colours in Mutilla?’ blue crayon


Mutilla is a genus of parasitic wasp of the family Mutillidae (velvet ants). In Descent 1: 366, CD reported that both sexes of M. europaea stridulated. Smith’s observation of stridulation in females of the genus had been given in the letter from E. W. Janson, 25 May 1868 (Correspondence vol. 16).
CD included Smith’s account of the beetle Trox sabulosus (the sand-loving trox) in Descent 1: 380.
Nicrophorus (Necrophorus is an incorrect subsequent spelling) is a genus in the family Silphidae (carrion beetles). CD discussed the stridulating organs of Necrophorus in Descent 1: 378–9.
Acalles is a genus in the family Curculionidae (snout beetles, weevils). CD mentioned the stridulation of Acalles in Descent 1: 384.
The reference is to Thomas Vernon Wollaston’s paper ‘On certain musical Curculionidae’ (Wollaston 1860); it was published in Annals and Magazine of Natural History, not the Zoologist. The paper is cited in Descent 1: 378.
CD reported his own observations of the stridulating mechanism in Mutilla europaea in Descent 1: 366.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

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

Wollaston, Thomas Vernon. 1860b. On certain musical Curculionidæ; with descriptions of two new Plinthi. Annals and Magazine of Natural History 3d ser. 6: 14–19.


On stridulation of Coleoptera, Trox sabulosus, Mutilla. [See Descent 1: 380.]

Letter details

Letter no.
Frederick Smith
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 82: A5–6
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6892,” accessed on 16 September 2021,

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