5 FARMERS’ BULLETIN 140. 
It is a matter of further interest that, with the exception of the 
European meadow ant, practically all of the ants which have been 
introduced into North America, either from the Old World or 
from South America, are such tropical species and potential house 
pests. All of these introduced species have been brought to North 
America and many of them given cosmopolitan distribution through 
the agency of commerce. The tropical ants in their native countries 
are still normally outdoor species, although in the Tropics they also 
frequent human habitations, including ships, and, by colonizing in 
ships’ cargoes, are easily given world-wide distribution. Some of 
Fic. 1.—The little black ant (Monomorium minimum): a, Male; b, pupa; c, female; d, same 
with wings; e, worker; f, larva; g, eggs; group of workers in line of march below. - All 
enlarged, the lettered illustrations all drawn to the same scale. (Original.) 
these Old-World species have become established as out-of-door 
species in the New-World Tropics, but in temperate regions they are 
able to survive only in dwellings, hothouses, mills, or other struc- 
tures where the requisite warmth is maintained. The ability of 
these imported tropical species to maintain themselves is largely 
due to the protection from competition with our native species 
afforded by this house-dwelling habit. 
None of these ants, with the exception, in rare instances, of the 
carpenter ant, are so destructive to household effects or supplies 
as they are annoying from the mere fact of their presence and their 
