174 Psyche [August 



ANTS OF THE GENUS FORMICA IN THE TROPICS 

 By William Morton Wheeler. 



The genus Formica belongs to the northern hemisphere and 

 is best represented in the north temperate or subboreal zone, 

 from wliich the number of species cHmishes rapidly towards the 

 pole and towards the equator. One species, Formica fusca, is 

 so eurythermal that it and its many varieties may be said to be 

 nearly coextensive in range with all the remaining species of the 

 genus. Certain data recently accumulated show that through 

 commerce a few of the species have succeeded in establishing 

 themselves in the tropics. These data and the original distri- 

 bution of the genus are briefly considered in the following 

 paragraphs. 



A map of the distribution of the genus Formica shows that 

 it covers nearly the whole of Europe as far north as North Cape, 

 where Sparre-Schneider (1909) has taken it between latitude 

 69° to 70° N., that is wdthin the arctic circle. In Asia the range 

 is even wider, since it probably reaches the same high latitude 

 and extends as far south as Soochow, China and the Himalayas 

 (28° to 30° N.). A corresponding southward distribution in 

 Europe is, of course, precluded by the Mediterranean. In the 

 New World Formica covers most of the Nearctic Realm. I 

 have shown (1913) that in Alaska F. fusca and its varieties 

 marcida Wheeler and neorufibarbis Emery range at least as far 

 north as 64° to 67°, that is up to Fort Yukon, on the arctic 

 circle. Eastward 7^. fusca occurs on the coast of Labrador, but 

 no Formicidse are known to exist in Greenland and Iceland, 

 according to Pjetum and Lundhein, cited by Forel (1910).- 

 Prof. Pilsud, Director of the Danish Biological Laboratory on 

 Disko Island, on the west coast of Greenland, has recently 

 confirmed this statement in my hearing. The southern range 

 of Formica in North America seems to stop at about 30° in the 

 United States. I have seen no specimens from Florida, but have 

 taken a couple of species near San Antonio, Texas and several 

 along the Mexican border in western Texas, New Mexico, 



