PSYCHE 
VOL. XXXIII. DECEMBER No. 6 
SEQUENTIAL DISTRIBUTION OF FORMICA EXSEC - 
TOIDES FOREL. 
By E. A. Andrews. 
Johns Hopkins University. 
Observations here recorded, indicate that the mounds made 
by this ant arise and pass away in rhythms harmonious with 
phases of forestation. 
The continued life of this species may indeed be dependent 
upon the migrations to new growths of trees. Trees that when 
young furnish food for the ant, when mature may cut off sun- 
light needed to make the mound a successful incubator for the 
young. 
Thus in fifteen years there has been found a migration of 
mounds comparable to the moving on of some primitive peoples 
dependent upon newly cleared forests. 
According to the book upon ants, and to other writings of 
that foremost student of these animals, Professor William Morton 
Wheeler; the most common mound building ant of North Amer- 
ica belongs in the species of Formica exsectoides Forel, and its 
mounds have been observed in Nova Scotia, Ontario, Maine, 
New Hampshire, Massachusetts, Connecticut, New York, New 
Jersey, Pennsylvania, Maryland, North Carolina, Georgia, Wis- 
consin, Illinois and Colorado, though there may be doubt as to 
all the extreme western forms being of the same species as the 
others. 
In general these ants are spread along the Appalachian 
region and are to be looked for in hilly or mountainous regions 
where the land is wooded more or less. It is thus exceptional to 
find these mounds near sea level as Wheeler observed them in 
Staten Island and as I have seen a few in Massachusetts ten feet 
