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 D^r Staudingers last Catalogue⁴

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