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Darwin Correspondence Project

From Francis Walker   24 June [1862]1

5 The Grove | Highgate

June 24th.

My dear Sir,

I received your letter today.2 The larger brown fly is Empis livida, & the smaller black fly is Empis pennipes, both females. The species of Empis habitually suck flowers, but the females feed also on small Diptera & chiefly frequent flowers for that purpose.3

I shall always be glad to send you any information in my power & believe me, | Yours truly | F. Walker


The year is established by the relationship between this letter and the letter to H. G. Bronn, 30 June [1862] (Correspondence vol. 10; see n. 3, below).
CD’s letter has not been found.
Empis livida and E. pennipes are species of dance fly. These species names were added to CD’s note in DAR 70: 13–14 on the observations of his sons William Erasmus Darwin and George Howard Darwin on the pollination of Orchis maculata; the note is dated 20 June 1862. CD incorporated these observations in the German translation of Orchids (Bronn trans. 1862, p. 22 n.; see Correspondence vol. 10, second enclosure to letter to H. G. Bronn, 30 June [1862]). In 1869, he published them in ‘Fertilization of orchids’, p. 142, a paper comprising revised and additional notes on orchids, keyed by page number to the first edition of Orchids (see also Collected papers 2: 139). Diptera is the order that includes mosquitoes, gnats, midges, and true flies.


Identified two flies as species of Empis that suck flowers, but the females also feed on small Diptera.

Letter details

Letter no.
Francis Walker
Charles Robert Darwin
Sent from
Source of text
DAR 70: 182
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10547,” accessed on 2 March 2021,

Also published in The Correspondence of Charles Darwin, vol. 24 (Supplement)