Volume HI, yuniher S 



A STUDY OF SOME SOCIAL BEETLES IN BRITISH 



GUIANA AND OF THEIR RELATIONS TO 



THE ANT-PLANT TACHIGALIA* 



By William Morton Wheeler 



Introduction. 



The materials for the following paper were obtained during 

 July, August and September, 1920, while I was working with 

 Prof. I. W. Bailey on the myrmecophytes of British Guiana. We 

 had gone to the Tropical Laboratory of the New York Zoological 

 Society at Kartabo for the purpose of making an intensive study 

 of the relations of the ants to such plants as Cecropia, Triplaris, 

 Cordia and Tococa; Prof. Bailey's investigations being primarily 

 concerned with the anatomical peculiarities of the plants, my own 

 with the identification and habits of their various ants. During 

 these investigations I encountered two species of beetles of such 

 unusual social habits that I was led to devote considerable atten- 

 tion to their behavior. They live in the fusiform enlargements 

 of the petioles of a singular tree, Tachigalia, which is also inhab- 

 ited by numerous species of ants. Both the beetles and the ants 

 cultivate coccids in the hollow petioles, and with the beetles and 

 coccids there are , moreover, several associated, parasitic or 

 synoeketic insects. And since there are also other insects, besides 

 those already mentioned, associated with the plant, we may 

 regard the latter as the focus of a very interesting and compli- 

 cated biocoenose. 



The elements of this biocoenose are so numerous and hetero- 

 geneous that I have had to appeal to several specialists for assist- 

 ance in making identifications and writing descriptions. Dr. E. 

 A. Schwarz and Mr. H. S. Barber kindly .studied and described 

 the social beetles and a little Coccinellid which feeds on their 

 coccids. Dr. Adam Boving made a fine study of the beetle larvse ; 



♦Contributions from the Entomological Laboratory of the Bussey In- 

 stitution, Harvard University. No. 188. 



