1919] Wheeler— The Ants of Tobago Island 113 



THE ANTS OF TOBAGO ISLAND. 



By William Morton Wheeler, 

 Bussey Institution, Harvard University. 



During April, 1918, Prof. A. L. Treadwell of Vassar College col- 

 lected such ants as he could find on the island of Tobago and sent 

 them to me for identification. The island is situated only twenty 

 miles northeast of Trinidad and is twenty-six miles long and seven 

 and one-half miles broad. Though it might be expected to have a 

 rich ant-fauna somewhat resembling that of Trinidad, Professor 

 Treadwell succeeded in taking only the following eight species: 



1. Odontoviachvs hoematoda L. Numerous workers of the typical 



dark form from Spey-Side. 



2. Solenopsis geminata Fabr. Numerous workers from Milford 



and Pigeon Point. 



3. Pheidole megacephala Fabr. A few soldiers and many workers 



from Pigeon Point and some other localities on the island, 

 "nesting in the sand of the seashore. " 



4. Pheidole fallax M-ayr suhsp. emilice Fore\. A single soldier from 



Pigeon Point. 



5. Acromyrmex octospinosa Reich. Two workers from Pigeon 



Point. 



6. Prenolepis (Nylanderia) longicornis Latr. Several workers from 



Spey-Side. 



7. Camponotus (Myrmothrix) abdominalis Fabr. Seven workers of 



the typical form of this variable species from Pigeon Point 

 and St. Patrick's Cathedral, "nesting in a calabash." 



8. Camponotus (Myrmamblys) fastigiatus Mayr. Eleven workers 



from Milford. 



Four of these ants, namely Odontomachus hwmatoda, Solenopsis 

 geminata, Pheidole megacephala and Prenolepis longicornis, are 

 everywhere abundant "tramps" in the tropics of both hemispheres. 

 The other four are common species of Trinidad and the adjacent 

 South American continent. The introduction of Pheidole megace- 

 phala into so small an island as Tobago must have led to the 

 extermination of any primitive or indigenous ant-fauna it may 

 have possessed. The few forms taken by Professor Treadwell 

 probably represent all or nearly all the species that are sufficiently 

 resistant or aggressive to withstand the inroads of such a pest as 

 megacephala. 



