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Darwin Correspondence Project

From A. G. Butler   2 June 1871

British Museum

2nd. June 1871

Dear Sir

I shall be glad to give you any information in my power respecting the sexes of Orgyia antiqua1   I always separated them in the larval state when breeding them in order to make use of the females for experimenting upon & as traps to entice males into my lizard-house, I have known a female attract five males in succession (but only on one occasion) & she died of exhaustion before laying her eggs.

I think Wallace has rather jumped to conclusions in some of his remarks on particular cases of mimicry. If you look at his description (Trans. Ent. Soc. 1869) of Diadema anomala you will see that he directly contradicts himself thus—p. 286 “A male from Borneo in the British Museum approaches the colouring of the female, being darker than my Malacca male, & having a brighter blue gloss on the outer margin & apical third of the anterior wings.” p. 287 “The males being always dull brown, the females glossed with rich blue.”2

We have two males scarcely differing from the females, & I believe the Malacca male to belong to another species: both sexes of D. anomala mimic probably the male of Euploea midamus, but in the white subapical spots of hindwings, they more nearly resemble a common Indian species E. Callithoë, representatives of which I am always hoping to see from the Malayan Archipelago.3

Secondly Mr. Wallace’s assertion respecting the independent mimicry of males should I think be received with caution4   indeed I strongly suspect that the males of Elymnias undularis are imperfect mimics of Euplœas of the E. Saundersii group,5 (at anyrate both sexes of a very nearly allied form from Borneo & considered to be a variety by Mr. Wallace, present the precise aspect of E. Saundersii & allies) whilst E. undularis ♀ mimics Danais chrysippus;6 a second case which I suspect in the same genus would be established by the union of Elymnias Kamara Moore as ♂ of E. Ceryx Boisd.7 E. Kamara clearly mimics a Euplœa & E. Ceryx a Danais; Mr. Trimen believes that he has discovered the model of Diadema Misippus Linn. ♂ in Danais (Amauris) Ochlea Boisd. whilst the ♀ mimics D. Chrysippus.8

Thirdly Mr. Wallace’s note (See p. 413 of Sexual Selection)9 respecting the more brilliant males in all Pieridæ is negatived entirely by the genus Callidryas10 the females of which not only present colours as brilliant as those of the males but often are adorned with borders of suffused crimson & orange & are always more abundantly marked with series of black spots than the males, these black markings throw up the yellows & reds & greatly increase the beauty of the insects; the two sexes but particularly the females show a considerable resemblance in their undersurface colouring to fading leaves, they however generally exhibit two or three bright metallic silver spots which must I think rather interfere with the resemblance, these spots are sometimes absent in the males but never in the females: again the ♀ of a pretty Haitian Terias just described by myself for the first part of this year’s Zool. Proc. exhibits a bright orange nebula on the outer margin of the hindwings; this colouring is entirely absent or at anyrate barely visible in the male.11

I am publishing a complete illustrated Monograph of Callidryas in my “Lepidoptera Exotica”;12 I could show you that the males of nearly allied species hardly differ whilst the females are widely distinct; I have been obliged to separate one species of old authors into five local species on account of the difference of the females

Believe me to be | yours very sincerely | A G Butler

CD annotations

1.1 I shall … eggs. 1.5] ‘other cases?’ blue crayon; ‘Colour or size’pencil
1.1 sexes of] ‘the ♀ is wingless— [Coleoptera] differ in colour— very rare circumstance—’ interl ink
4.1 assertion] ‘negation’ pencil
4.1 males] underl blue crayon; reverse question mark in margin blue crayon; ‘fe’ inserted before ‘males’, blue crayon
5.1 Thirdly … Callidryas 5.2] double scored blue crayon
5.2 the females … the insects; 5.6] triple scored red crayon
5.7 undersurface] underl blue crayon
5.8 they however … male. 5.13] scored red crayon
5.8 bright metallic] underl blue crayon
5.9 sometimes … females: 5.10] underl blue crayon
6.2 I could … distinct; 6.3] heavily scored red crayon
6.2 I could … females 6.5] scored blue crayon; ‘But [‘the’ del after caret] is not this exceptional?’ added blue crayon
Top of letter: ‘Descent’ red crayon; ‘2’ red crayon, circled red crayon
Verso of last page: ‘Jackal scratch backward’ pencil, del pencil

CD note:

Feb. 22 /72/ I have seen the 2 sexes of some species of Callidryas & the ♀ considerably [after del illeg] more brilliantly-coloured.— It is very interesting that the ♂s here, as I saw, are very much more like each other than are the ♀— this is an exception which almost proves the rule.— In Nature Mr Butler has described case in which ♂ imitates,13 & there are other somewhat doubtful cases, whilst the ♀ does not imitate other species— But this genus Callidryas has ♀ more beautiful than males & so it complies with rule


In his letter of 26 May 1871, Butler had noted that since the sexes of the moth Orgyia antiqua (the vapourer) were dimorphic in the larval stage, he was able to determine that the number of males greatly exceeded that of females. CD’s letter has not been found.
Butler refers to Alfred Russel Wallace and Wallace 1869b. The butterfly Diadema anomala is now Hypolimnas anomala (the Malayan eggfly). It belongs to the subfamily Nymphalinae.
Euploea midamus (the spotted blue crow) belongs to the subfamily Danainae (milkweed butterflies). Euploea callithoe (now considered a subspecies of E. phaenareta) is native to New Guinea.
No published statement by Wallace on independent mimicry in male butterflies has been found, but in Descent 1: 414–15 n. 31, CD reported Wallace’s belief that no male butterflies had protective coloration that was not shared by females of the same species. In [Wallace] 1867b, p. 37, Wallace had argued that in general females were duller than males for protection; he had accounted for some female butterflies being more brilliantly coloured than males of the same species as result of protective mimicry.
Butler refers to Euploea saundersii as a ‘species group’; that is, the several closely related or similar species of which E. saundersii is the principal exemplar. ‘Species group’ is not an official taxonomic rank, but is used for convenience.
Danais chrysippus (now Danaus chrysippus) is the plain tiger butterfly.
Elymnias kamara and E. ceryx are still recognised as distinct species, each of which has currently recognised subspecies.
Butler refers to Roland Trimen and to Diadema misippus (now Hypolimnas misippus, the Danaid eggfly). Amauris ochlea (Danais ochlea is now a junior synonym) is the novice butterfly. In addition to being sexually dimorphic, the Danaid eggfly has three recognised female morphs.
See Descent 1: 413.
Callidryas is now Phoebis, a genus of sulphur butterflies (subfamily Coliadinae), in which females tend to be a deeper shade of colour than the males.
Butler’s description of Terias memulas is in Proceedings of the Zoological Society of London (Butler 1871, p. 251).
Butler’s Lepidoptera exotica (Butler 1874) was first published in twenty parts between 1869 and 1874. His ‘Monograph of the genus Callidryas with figures of the typical forms of the different species’ was incorporated in the larger work (see Butler 1874, pp. 22–4; 30–2; 35–7; 43–5; 56–62; 67–9; 75–6; 92–6; 105–8; 118–22; 142–8; 153–5).
Butler wrote of the mimicry of males of Belenois by males of Mylothris (both in the subfamily Pierinae) in a letter published in Nature, 29 December 1870, p. 165.


Facts contradicting Wallace’s views on coloration of Lepidoptera.

Letter details

Letter no.
Arthur Gardiner Butler
Charles Robert Darwin
Sent from
British Museum
Source of text
DAR 89: 108–111
Physical description
7pp ††

Please cite as

Darwin Correspondence Project, “Letter no. 7797,” accessed on 23 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 19