1956] 
Creighton — Ephebomyrmex 
61 
few centimeters high. The workers make no attempt to 
cut down the surrounding vegetation which often grows 
on the crater immediately around the entrance.” 
It is hard to see what Wheeler had in mind here. Neither 
subdentatus nor apache (or its synonym sancti-hyacinthi) 
are small species. Indeed the major worker of apache 
is one of our largest species, being surpassed in this 
respect only by the major of badius. While the number 
of individuals in a nest of apache is small, there is 
ordinarily no crater nor disc around the nest entrance 
and this paucity of excavated material is, as Cole has 
recently shown (10), one of the characteristics of this 
species. The colonies of subdentatus ordinarily contain 
at least 500 individuals and this species usually constructs 
a ragged disc of gravel, not a crater, around the nest 
entrance. The nests of desertorum , while less populous 
than those of subdentatus , are far larger than those of 
imberbiculus and pima, and the coarse, flattened gravel 
mounds which desertorum customarily makes are wholly 
unlike the delicate craters constructed by our represent- 
atives of Ephebomyrmex. I mention these inconsistencies 
because it is certain that they have obscured Wheeler’s 
original clear-cut presentation of the habits of imberbiculus. 
As far as the writer has been able to determine the 
habits of imberbiculus and pima are so similar that a 
single account will cover both species. On rare occasions 
these ants will nest beneath stones but in most cases 
they build their nests without any covering object. The 
soil selected is always hard-packed and usually of a rather 
fine, sandy texture. There is a single, small nest entrance 
not more than 3 or 4 mm. in diameter, and the passages 
which lead from it are equally delicate. The storage 
chambers are small. Both the storage chambers and the 
passages collapse very easily if the nest is excavated 
and this makes it unusually difficult to trace them. The 
only practical method for doing so that the writer has 
found is to excavate the nest very gradually and allow 
time between excavations for the workers to reopen the 
caved-in passages. If three or four days can be devoted 
