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Darwin Correspondence Project

From Frederick Smith   8 October 1869

British Museum

8th. Octr. 1869.

My dear Sir

I have carefully watched the Mononychus pseudacori and am satisfied that both sexes stridulate— I have placed them singly in pill boxes with glass lids and if they are placed in a strong light—sunlight or lamp light they become musical— I send a few in a quill so that you may experiment if you have leisure to do so—1

I also feel certain that both sexes of the Musk-beetle Aromia moschata—are musical— the same I believe of all the species of Necrophorus—2 Among the Orthoptera on the contrary as far as I know only the Males stridulate—

I kept the Acheta in June last in my garden and the male somewhat annoyed my neighbours by his loud piping sound. This was A. campestris from Surrey— the same of course is the rule with all the Crickets as well as the Cicadas3

Yours sincerely | Fredk Smith

CD annotations

1.1 Mononychus] underl pencil; ‘n?’ added pencil
1.1 and … stridulate— 1.2] double scored pencil
1.1 I have … do so— 1.4] ‘Add after or before Frank’s statement’4 blue crayon
2.2 the same … Cicadas 3.3] crossed pencil
Top of letter: ‘Mutilla5 | Mononychus’ pencil; ‘(Mononychus)’ ink; square brackets in original MS


Mononychus pseudacori, the single-clawed weevil, is now M. punctumalbum, the iris weevil (family Curculionidae). In Descent 1: 382, CD cited Smith for the information on stridulation in both sexes.
Aromia moschata is in the family Cerambycidae (longhorn beetles). The genus Necrophorus belongs to the family Silphidae (carrion beetles).
Acheta campestris is now Gryllus campestris, the field cricket. It was in the family Achetidae but now belongs to the family Grillidae (crickets, grasshoppers, and katydids).
In Descent 1: 382, CD cited Frederick Smith’s observations on Mononychus pseudacori after his son Francis Darwin’s observations on Geotrupes stercorarius.
In Descent 1: 366, CD discussed stridulation in Mutilla europaea, the velvet ant. See also letter from Frederick Smith, 14 September 1869.


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


Both sexes of Mononychus pseudacori and other Coleoptera stridulate.

Letter details

Letter no.
Frederick Smith
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 82: A3
Physical description
2pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6926,” accessed on 23 September 2021,

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