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 which the number of species dimishes rapidly towards the 
pole and towards the equator. One species, Formica fusca, is 
so eury thermal 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 within 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 F. 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, 
