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Darwin Correspondence Project

From Henry Doubleday   28 March 1868


March 28th 1868

My dear Sir,

⁠⟨⁠several lines excised⁠⟩⁠

A year or two since some discussion arose at a Meeting of the Entomological Society about the insects commonly called “death-watches” and my old friend Frederick Smith said that, in his opinion, the ticking sounds occasionally heard in old buildings and which were generally attributed to Anobium tesselatum and Atropos pulsatoria were not produced by insects— Soon after I read the report of the meeting I wrote to him and said that he was certainly wrong about the Anobium and I would endeavour to procure him some living specimens the following spring.1 I was fortunate in finding four or five and they soon convinced him of his mistake— it is not a very easy thing to get hold of them as when disturbed they immediately drop and feign death and are then difficult to ⁠⟨⁠several lines excised⁠⟩⁠2 I will send them to you.

My reason for supposing the ticking sound to be a sexual call is that I have in two or three instances I have found a female by the ticking sound and an hour or two afterwards seen her in copulation— last spring there was one ticking on a piece of paper and the next morning she was in copulation and three or four more males were sitting on the paper— I do not at all know which sex ticks first but probably the female—this, however is difficult to prove—some other insect certainly produces a fainter and more continuous ticking sound which I suspect is the Atropos but I have no positive proof of the fact —

Last spring Mr Llewelyn of Neath captured two pairs of Tephrosia crepuscularia in copulation—3 in both cases one was the typical colour the other the black variety— he obtained a lot of eggs and has succeeded in rearing about one hundred and twenty moths— he says in his last letter: “the proportion between dark and light specimens is almost equal to one, but the males are more numerous than the females”   he sent me twenty-four specimens, twelve light and twelve dark-coloured—and thereon seven females and seventeen males and I expect this is about the proportion the sexes bear to each other or he would have sent me more females—

Mr Llewelyn’s remark about the sexes was made without my having said anything to him on the subject.— In all the priced Continental catalogues of Lepidoptera the females are generally higher than the males and many of the specimens are reared from the larvae— I will give you two or three extracts from Dr Staudingers last Catalogue4

Thais Cerisyi 12 : 25
" Rumina 10 : 15
Anthocaris Damone 30 : 50
" Gruneri 20 : 50
Colias pelidne 12 : 20
Thestor Ballus 5 : 10

and so on with all the rarer species—5 of course any number of such common species as rapæ, napi Phlæas, Alexis &c can be procured and no difference is made in the price of the sexes—6

I cannot account for the difference said to have been observed in the proportion of the sexes between bred and captured specimens— I do not remember an instance of my having more females than males in a brood of any species of Lepidoptera—when larvæ are beaten into a net I have no doubt that all are taken but when hunted for with a light at night, the larger larvæ of the females are certainly more readily seen— with best wishes believe me

My dear Sir | Yours very sincerely | Henry Doubleday

Charles Darwin Esq

CD annotations

2.5 I do … female— 2.6] scored red crayon
2.7 ticking sound] ‘which I suppose is Atropos’ added after, ink
2.7 which … fact— 2.8] crossed ink
3.1 Last] after opening square bracket, blue crayon
3.5 but … females] double scored blue crayon
3.6 seven … males 3.7] double scored blue crayon
4.2 In all … larvae— 4.4] double scored blue crayon
5.2 I do not … Lepidoptera— 5.3] double scored blue crayon
5.5 the larger … seen—] double scored blue crayon
Top of letter: ‘I tried & ⁠⟨⁠  ⁠⟩⁠ answered by ticking’ pencil
Top of second page: ‘H. Doubleday’ ink
Table: double scored blue crayon


The exchanges Doubleday refers to are reported in Transactions of the Entomological Society of London (Journal of Proceedings) 3d ser. 2 (1864–6): 130–1 and 5 (1865–7): iii–iv. Anobium tesselatum, the death-watch beetle, is now Xestobium rufovillosum (personal communication, Bryan Turner, King’s College London); Atropos pulsatoria is now Trogium pulsatorium (Smithers 1967, p. 13).
In Descent 1: 385, CD cited Doubleday on Anobium tesselatum ticking and included a quotation, which may be part of the excised portion of this letter: Mr. Doubleday informs me that ‘the noise is produced by the insect raising itself on its legs as high as it can, and then striking its thorax five or six times, in rapid succession, against the substance upon which it is sitting.’
Doubleday probably refers to John Talbot Dillwyn Llewelyn, who was then living at Ynisygerwn, Neath, near Swansea in Wales (personal communication, Richard Morris). Tephrosia crepuscularia is now Ectropis crepuscularia, the small engrailed moth.
The reference is to Otto Staudinger and to the sale catalogues he produced from the late 1850s (see Iris 13 (1900): 349). In Descent 1: 312, CD cited Doubleday for calling his attention to Staudinger’s catalogues.
Thais Cerisyi is now Allancastria cerisyi, the eastern festoon; T. rumina is now Zerynthia rumina, the Spanish festoon; Anthocaris damone is now Anthocharis damone, the eastern orange tip; Anthocaris gruneri is now Anthocharis gruneri, Grüner’s orange tip; Colias pelidne is the blueberry sulphur; Thestor ballus is now Tomares ballus, the Provence hairstreak.
The butterflies referred to are Pieris rapae, the cabbage white, P. napi, the green-veined white, Lycaena phlaeas, the small copper, and Glaucopsyche alexis, the green-underside blue.


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

Smithers, C. N. 1967. A catalogue of the Psocoptera of the world. Australian Zoologist 14 (1967–8): 1–145.


On the proportion of sexes in moths; Lepidoptera females command higher prices; quotes Staudinger’s catalogue [see Descent 1: 311–12].

Ticking of Anobium tessellatum [see Descent 1: 385].

Letter details

Letter no.
Henry Doubleday
Charles Robert Darwin
Sent from
Source of text
DAR 82: A11–12, DAR 86: A94
Physical description
ALS 4pp inc †

Please cite as

Darwin Correspondence Project, “Letter no. 6064,” accessed on 17 September 2023,

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