1921] Wheeler: Some Social Beetles 91 



ies is that of a feeble, anaemic and harried species on the verge 

 of extinction. 



General Considerations 



The behavior of the social Silvanids described in the pre- 

 ceding pages and the conditions under w^hich they live are suf- 

 ficiently startling to stimulate reflection and a comparison with 

 other species of the same and allied families. Such comparison, 

 as an ethological method, has so often thrown light on what ap- 

 peared at first sight to be unique and incomprehensible instincts 

 and their settings that we may hope by resorting to it to trace 

 the peculiar conditions in Coccidotroph^is and Eunaiisibius to 

 simpler and more general phenomena. Since both the setting, 

 or environment and the responses, or behavior of the beetles are 

 rather complicated it will be best to consider them separately and 

 to begin with the setting, i.e. with the Tachigalia biocoenose. 



The general ethological concept of the 'biocoenose' was, of 

 course, more or less clearly recognized by many of the early zoolo- 

 gists. Although the term seems to have been first used by M6- 

 bius (1877), even Reaumur had an inkling of the value of study- 

 ing insects in association with their host plants. He says : "I 

 would that the observers who busy themselves with the history 

 of insects gave catalogues of those that feed on every plant." 

 In the middle of the last century Perris (1852-1862) devoted 

 many years to the study of the insects associated with the mari- 

 time pine and the chestnut in France, and Kaltenbach (1874) 

 attempted to list all the phytophagous insects of Germany accord- 

 ing to their host plants. In the United States Packard's volume 

 (1881) on the forest and shade-tree insects and Mrs. Dimmock's 

 paper (1885) on the insects of the birch represent more modest 

 studies of the same kind. Perhaps none of our entomologists 

 has been more thoroughly convinced of the advantages of study- 

 ing insects and other animals as components of biocoenotic com- 

 plexes than Forbes. Forty years ago he expressed his general 

 convictions on this subject in his paper on the food of fishes and 

 insects (1880) and he has returned to the subject in a recent 

 address (1915). His fine papers on the strawberry and maize 

 plants and their associated organisms (1884, 1894-1905) also 

 clearly illustrate the great value of biocoenotic investigations. 



