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Darwin Correspondence Project

From Thomas Belt   2 August 1873

Ryton, Blaydon-on-Tyne

Augt 2 1873

My Dear Sir,

I am taking the liberty to enclose for your perusal some observations I am about to publish, in a work called “the Naturalist in Nicaragua”, on the honey glands of plants & the honey secretions of aphides &c.1 Would it be asking too much to request you to look them over and inform me if the explanations given of the use of the honey secretions are fully proved by the facts I have given. In the book which will be published by Murray in October I have also ventured some remarks on the loss of a hairy coat by the Hairless dogs of Central America shewing how it might have been of great use to them to lose it.2 I should have enclosed these observations also but was afraid to take up too much of your time which must be fully occupied

With regard to ants being apparently afraid of passing a line over which the finger has been rubbed I think it is not fear but perplexity at their scented trail having been disturbed— I think when a pioneer ant discovers any food it runs back to the nest scenting its trail as it goes along and other ants follow this up. I have noticed some curious facts about this in my book and have completely disconcerted a line of ants for some time by simply scraping off a little of the surface soil over which they were passing.3 The intelligence of ants is wonderful and I have been an observer of them in the tropics for several years

On other side I give a list of some of the subjects I have made notes about & which I shall be happy to send you—if you would be interested in seeing my manuscript before it is published in October

Yours very truly | Thomas Belt

Ecitous4 or Foraging Ants

Examples of their intelligence

Parallel between the mammalia and ants

Leaf cutting ants

They are fungus growers and eaters—

Examples of their sagacity

Flowers fertilized by birds

The hairless dogs of tropical America

The cause of sterility between allied species


The enclosure has not been found. For Belt’s observations on the symbiotic relation between ants and the plants and insects that secrete honey-like substances, see Belt 1874, pp. 222–9.
Belt 1874 was published by John Murray in December 1873 (Publishers’ Circular, 18 December 1873, p. 1062). Belt described hairless dogs in Belt 1874, pp. 205–9, and concluded that hairlessness might have been beneficial in reducing the incidence of parasites.
See Belt 1874, pp. 23–4. CD had earlier forwarded letters from James Duncan Hague on this aspect of ant behaviour to Nature (see second letter to Nature, [before 3 April 1873], and letter to Nature, [before 24 July 1873]).
Belt refers to the genus Eciton (a type of army ant).


Sends extracts, from his forthcoming book [The naturalist in Nicaragua (1874)], about the secretion by plants of honey to attract the protection of ants. Invites CD’s comments.

Letter details

Letter no.
Thomas Belt
Charles Robert Darwin
Sent from
Source of text
DAR 160: 128
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8995,” accessed on 3 March 2021,

Also published in The Correspondence of Charles Darwin, vol. 21