SOCIAL LIFE 249 



munity. Such " myrmecophiles " have been extensively 

 studied in recent years, and for details as to their relations 

 to ants the writings of E. Wasmann (1920) may be advantage- 

 ously consulted. Many of the ant guests contribute 

 nutrient material on which the ants feed. Of these the 

 aphids (*' greenfly ") and some allied Hemiptera are the 

 best known. As previously mentioned in this chapter 

 (p. 241), the aphids, sucking sap in great quantity from 

 plants, void from their intestines drops of the surplus 

 food substance, of which they can use but a small proportion 

 for their own sustenance. The fluid evacuated by the 

 aphids is therefore not excreted waste-matter but digested 

 fluid food in which much of the sugar has undergone 

 inversion. Aphids therefore furnish an extensive and con- 

 venient source of food supply to the large proportion of ants 

 that live principally or entirely on '' honey-dew." To 

 obtain the liquid ants may follow the " greenfly " as they 

 feed on plant-shoots, or, in the case of root-sucking aphids, 

 harbour them in their nests. Ants in attendance on 

 aphids may be observed stroking them with feelers or 

 fore-legs, and the aphids in response exude drops of honey- 

 dew which the ants swallow. 



Besides aphids, scale insects and mealy bugs (Coccidae) 

 and sucking insects (Homoptera) of other allied families 

 are harboured by ants for the sake of the honey-dew voided 

 from their intestines. There are many records of the care 

 taken by the various kinds of worker- ants of young, new- 

 born aphids, root-sucking kinds being carried by the ants 

 to fresh rootlets especially soft and succulent. While such 

 underground aphids are herded by their ant guardians 

 within specially constructed earthen " pens," some aphids 

 and coccids that feed on the shoots of plants are gathered 

 into droves by the ants, which build over them covers of 

 silky or papery substance beneath which they are protected 

 and sheltered. Wheeler points out that certain features 

 of structure and behaviour observ^able in these ants that 

 feed on honey- dew and in the sucking insects that supply 

 their food, confirm the opinion that the relation between the 



