To Otto Staudinger   20 May 1868

Dear Sir

I thank you sincerely for your most kind and interesting letter.¹ It is a great disappointment to me that I may not trust to your List in relation to the sexes of Lepidoptera; but I am not the less obliged to you for having saved me from falling into error.² It would be a very interesting point if you could prove that the females were the most liable to perish in coccoon-state; but, as I understand your letter, this is at present only your belief.³ I am particularly glad to hear of the remarkable fact of the hybrid moths being all males. This fact will come in very useful for me to quote.⁴ I quite agree with what you say, that entomologists have the best means of proving the derivation of species, & I have often much wished that I was one of the class, but it evidently requires the labour of a life to study carefully even one division of so gigantic a class.

With very sincere thanks & my best respects, I remain, dear Sir | Yours faithfully | Charles Darwin