1952] 
Creighton — Pseudomyrmex apache 
141 
Chihuahua: 
Sierra de en Medio: Nogales Ranch (5000') five colonies 
in Q. emoryi or Q. ohlongi folia. 
Texas : 
Fowlerton (300') La Salle Co., one colony in Prosopis 
juliflora; Monte Alto (60'), Hidalgo Co., two colonies 
in P. juliflora. 
California : 
Agua Tibia Mountains: Dripping Springs (1500') two 
colonies in Q. chrysolepis . 
The records cited above show that Ps. apache occurs 
most frequently in mountainous areas at elevations between 
2500 and 6000 feet. In such stations it ordinarily nests 
in evergreen oaks but, when the range descends below the 
oak belt, it will nest in mesquite. Whether the ants nest in 
oak or mesquite they select a good-sized branch or the trunk 
of the tree as a nest site. They seldom nest in twigs and 
this response is striking in view of the fact that twigs are 
a favorite nest site for our eastern species. The branches 
selected by apache are those through which wood-boring 
insects have driven passages. The ants carefully clean 
these passages of the detritus left by the insects which made 
them. In most cases the passages have a diameter several 
times as great as that of the ants, hence it would seem 
that the ants could be jarred out of the open ends of the 
passages without difficulty. This is not the case, for they 
cling to the walls with great tenacity. To get all the speci- 
mens out of a nest it is usually necessary to split the branch 
into small pieces so that all the passages are exposed. Ps. 
apache is not at all pugnacious. It will bite on occasion but 
it very rarely stings and the sting is not painful. Since 
many species of Pseudomyrmex , some much smaller than 
apache , sting severely on the slighest provocation, this be- 
havior is rather surprising. 
The female of apache often becomes physogastric after 
the colony is well established. The intersegmental mem- 
branes do not bulge but are stretched tight between the 
separated gastric sclerites. Since the latter retain their 
curvature, the gaster of a physogastric female of apache 
looks like a white tube running through a series of close- 
