Ɛpsilon

From J. H. Comstock   4 June 1880

J. Henry Comstock. | Entomologist to the | U.S. Department of Agriculture. | Washington, D. C.,

4 June 1880.

PERSONAL

Mr. Charles Darwin, | Farnborough Hants, Kent Co., England.

Sir:

I have requested that a copy of my Report on Cotton Insects, recently published by this Department, be sent to you.1 Knowing that your time is fully occupied I take the liberty of indicating the parts of the Report which I think will be of interest to you. The cotton worm (Aletia argillacea) is doubtless a tropical insect which has been introduced into our territory; as yet however, it is not fully naturalized and but very few are able to survive our winter.2 Thus the first brood in the spring is so small that it is seldom noticed (see p.97). In the course of the season the insect passes through several generations, frequently increasing in numbers to such an extent as to sweep away the entire cotton crop of large sections of country. But of the immense numbers thus produced only a few individuals ever survive the following winter (see pp.90, 91). Is not this a remarkable instance of the action of natural selection where hardly one insect in five hundred thousand is preserved?

Another point which I think will be of interest to you is the structure of the maxillae of the adult Aletia (see pp.86,87).3

I think you will also be interested in the extra floral nectar glands to which I have referred on pp.84,85 and which are discussed more at length by Mr. Trelease pp.319–333.4

Yours very respectfully | J. Henry Comstock.

TLS

1
An annotated copy of Report upon cotton insects (Comstock 1879) is in the Darwin Library–CUL.
2
Aletia argillacea is a synonym of Anomis argillacea (cotton leafworm or cotton worm). It is a moth of the family Erebidae (the same family as the moth described in F. Darwin 1875; see n. 3, below).
3
In Comstock 1879, p. 87, Comstock cited F. Darwin 1875 and Orchids. Comstock had noted that in the adult moth, the maxillae possessed spines on the dorsal surface, enabling the organs to be used to pierce fruit. Francis Darwin had discussed similar adaptations in a related moth, Ophideres fullonica (a synonym of Eudocima phalonia, the Pacific fruit-piercing moth).
4
Comstock 1879, pp. 319–33, was a chapter by William Trelease, ‘Nectar; what it is, and some of its uses’. It was followed by an extensive bibliography, including Cross and self fertilisation and Variation. Passages on these pages are scored in CD’s copy (see Marginalia rev. ed.).

Please cite as “DCP-LETT-12621,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-12621