1921] Wheeler: Some Social Beetles 93 



comprising all the trees it habitually defoliates, its fungus gar- 

 dens, its myrmecophiles of the Blattid genus Attaphila, the toads, 

 lizards and ant-eaters which feed on the foraging workers, the 

 Amphisbaenians which live in the penetralia of the huge nests, 

 etc. The two ants, Camponotvs femoratus and Crematogaster 

 parabiotica, which attend Membracids on the young shoots of 

 the Tachigalia, are really characteristic members of the very 

 peculiar "ant-garden" biocoenose, which I have described in an- 

 other paper (1921), and the Dolichoderus attelaboides belongs 

 to still another biocoenose of which many Melastomaceous plants 

 and their Membracid parasites are important components. 



A particular biocoenose must also, of course, have a phylo- 

 genetic history, i.e. we must conceive it to have been gradually 

 built up, integrated and organized in time from components 

 which detached themselves from other biocoenoses and attached 

 themselves as satellites to an organism which furnished more 

 congenial conditions of life. Owing to the basic nutritive inter- 

 dependance of animals and plants, a particularly favorable plant 

 usually constitutes the primary focus of a biocoenose. The vari- 

 ous parasites, scavengers and synoeketes, which live with the 

 insects that immediately depend on this plant merely use the 

 former as so many secondary or tertiary foci. Thus in the 

 Tachigalia biocoenose the primary focus is the young plant 

 and the center of the focus the leaf-petiole, the secondary focus 

 is represented by the coccids and the tertiary foci by the ants 

 and beetles to the extent that they attract predators, parasites 

 and scavengers. 



It is permissible, perhaps, to reconstruct the phylogenetic 

 sequences of the various organisms that have become associated 

 to form the Tachigalia biocoenose. Not improbably the tree, like 

 many other trees of the Neotropical jungle, was originally peo- 

 pled throughout its life by a certain number of miscellaneous, 

 inquiline ants. Among these were several species of Pseudo- 

 myrma and Azteca, both large genera comprising numerous forms 

 which still habitually inhabit any available hollow twigs or peti- 

 oles of the most diverse trees and shrubs. Later the number 

 of these ants was reduced, through the advent of the coccids and 

 their definitive association with the Tachigalia, to a very few 

 species, the putative ancestors of the present Ps. damnosa and 



