HOMOPTERA 



ATTENDANCE BY ANTS 



The attendance by ants on various species of Membracida has often been recorded. Interesting 

 notes have been published on this subject by Belt (1874), Rice (iSgS), Green (1900), Baer (igoS), 

 Buckton (1903), Poulton (igoS), Bianch (i9i3) and Lamborn (1914), and attention has been called to 

 thefact by many other authors. The writer (19x73) listed a considerable number of myrmecophilous 

 species of northeastern United States with the species of ants associated with these forms. 



The mutual relationship belween these two kinds of insects offers a most interesting field for 

 study and opportunities for delightful and fascinating observations of the insects in their natural habi- 

 tats. In general this relationship seems to be about the same as that shown between ants and other 

 myrmecophilous Hemiptera, particularly the aphids and coccids, and the symbiosis is apparently one 

 of mutual benefit, but there are a number of unsolved problems regarding the factors involved which 

 iieed further study. 



One of the first of these problems is suggested by the fact that some species are always attended 

 by ants while others are never attended although there are apparently no physiological differences to 

 cause the distinction. For example, in North America, the genus Ceresa, which is very well repre- 

 sented in species and in individuals, is, so far as is known, never found in association with ants, while 

 the genus Telamona, almost equally well represented, seems always to be attended. Another problem 

 arises from the fact that certain species attended in one locality have never been reported as being 

 attended in other locahties, even in the same general region. As an illustration, ants are usually 

 found with the nymphs, at least, of Stictocephala inermis in eastern United States but have never 

 been seen with the same species in Texas. Again, it sometimes happens that a specieswhich is always 

 attended wherever it is found, has a close relative in the same genus and in the same locality which is 

 never attended. This is true of several species of Gargara in the Orient. The questions suggested by 

 these facts cannot be answered on the basis of abundance or distribution nor on the factor of the pro- 

 duction of the anal secretion which attracts the ants. For example, Enchenopa binotata, one of the 

 commonest species in the United States, with a wide distribution and an enormous number of indiv. 

 iduals, is, so far as is known, never attended by ants, although the nymphs of this species have the same 

 extended anal tube and secretes a fiuid as do those of the myrmecophilous forms. Moreover, they are 

 so abundant that they should be easily discovered by the ants if there were any occasion for a mutual 

 relationship. 



The species of ants attending Membracida seem to be common to all the Membracida concerned in 

 a given region. Where two species of Membracida are abundant on the same host at the same time, the 

 same kind of ants may be found attending both species, but the same individual ant has never been 

 observed to go from one species to the other in collecting the secretion. The number of species of ants 

 attending membracids in any one area seems to be rather limited. The species collected in eastern 

 United States by the writer and determined by W. M. Wheeler, include Formica obscuriventris Mayr., 

 Formica exsistoides Forel, Camponotus pennsylvanicus De Geer, Crematogaster lineolata Say, Prenolepis imparis 

 Say and Formica fusca Fabr. Since only those species are recorded which were actually observed 

 taking the secretion from the membracid, it is likely that the above list of species is not at all complete 

 for the region. From other records in the literature it would appear that the Formica in North America 

 are oftenest noted as attending Membracida. Professor Wheeler, in determining ants taken with South 



