Dear Darwin

I send a few notes on Fritz Muller’s letter which I have read with much interest.¹

1. Hesperidæ. I doubt this being a general fact. An immense group of hundreds of species, carry their wings expanded, & they comprise many gay-coloured but more dull species. The majority carry the wings erect, and many of these have the upper side (concealed in repose) very brilliant,—most however being dull.²

2. Preference of colour. The fact about Callidryas philea visiting red flowers is good,—but I should like much more extended observation before deciding that it was a preference for one colour over another that decided it,—except as being more conspicuous and therefore attractive, as a flower, at a greater distance.³

3. Commencement of Mimicry. I do not see the difficulty in Leptalis mimicking 3 widely different forms.⁴ It might be if we suppose Leptalis to have begun to vary from the original white-butterfly type, after the forms it mimics had acquired all their distinctness. But probably mimicry commenced at a very early stage of the existence of all these groups, when their characteristic styles of colouring had not been acquired,—when they were all simpler & more alike, & when different races of Leptalis might easily be modified so as to resemble them all. Variation & mimickry would thenceforth go on together.

4. Abundance of mimicking form, rarity of that mimicked.

St^a Catherina is near the Southern limit of the groups mentioned & conditions may easily be unfavourable there to a species very abundant in the place where the mimicry originated.⁵

5. Imperfect resemblance.

I do not think that the resemblance quoted between Eresia langsdorfii and Heliconia phyllis is too imperfect to serve as a protection.⁶ At a little distance on the wing I think it might be a good imitation, especially if the rufous patch were very bright when I have noticed the resemblance of that colour to red when seen against green or any other good contrasting colour. The exact tint of the colour is of less importance than the shape & size of the patch, & the general outline.

The band or oblique stripe of white is such a common character in widely different groups of butterflies that I cannot look upon it as mimetic, though under favourable circumstances its presence may aid in the production of mimicry.

6. Male attracted by mimicking female.

This would be very important if truly interpreted,—but butterflies so continually follow & flutter around other species for a few moments, that the value of the observation is very much weakened.

7. The idea of sexual selection leading to a copy of other more brilliant species, is to my notion a “very wild” supposition.⁷ “Nature” would certainly be glad of the letter.⁸

Yours very truly | Alfred R. Wallace

C. Darwin Esq.