The Use of Ants to Aphides and Coccidæ

Abstract

I HAVE just had an opportunity of seeing Dr. Romanes' interesting work, “Darwin, and after Darwin,” and find therein (p. 292) the production of honey-dew by Aphides adduced as a difficulty in the way of the Darwinian theory. I have not paid any particular attention to Aphides, but have lately been much interested in the allied Coccidæ, which, since they produce a similar fluid attracting ants, may be considered to offer a parallel instance. Both Coccidæ and Aphides suffer from many predaceous and parasitic enemies, and there seems to be no doubt that the presence of numerous ants serves to ward these off and is consequently beneficial. There is an interesting. Coccid, Icerya rosæ, which I find on Prosopis here, and on more than one occasion I have been unable to collect specimens without being stung by the ants. At the present moment some of these Iceryæ are enjoying life, which would certainly hare perished at my hands, but for the inconvenience presented by the numbers of stinging ants.