IO 
Psyche 
[March - June 
the antennae and these were held so closely against the head that 
the Pogonomyrmex workers were seldom able to grasp them. If 
these attacks were vigorously pressed the militicida major usually 
stood perfectly still and waited until the mandibles of its opponent 
were near its own. It then lunged forward, closed its jaws on the 
mandible of the Pogonomyrmex worker and attempted to break of! 
the crushed mandible. The majors did not always succeed in doing 
so, particularly in the case of maricopa, whose heavy mandibles are 
hard to break, but they seldom failed to mangle the mandible so 
badly that it was useless. It may be added that this attack on the 
mandible is deliberate, for the militicida major will rarely strike at 
other parts when these are presented. We have repeatedly seen the 
Pogonomyrmex workers thrust their antennae or legs between the 
open jaws of the militicida major without causing the major to 
strike. They do not do so until there is a good chance that the 
mandible can be grasped and they rarely miss their target. After 
a number of Pogonomyrmex workers had been put out of action 
with useless mandibles, or sooner if the Pogonomyrmex workers did 
not press the attack vigorously, the militicida majors emerged from 
the passage and began a different sort of action. They no longer 
faced their opponents and struck at their mandibles but approached 
them from the rear and struck at the thorax or the petiolar nodes. As 
a result, most of the Pogonomyrmex workers were ultimately cut in 
two, either at the petiole or behind the pronotum. In this more open 
fighting it was also obvious that the petiolar nodes and the mesothoracic 
area were the principal targets. An examination of the Pogonomyr- 
mex workers at the end of an engagement always showed much 
damage to mandibles, thorax and petiolar nodes and surprisingly 
little damage to legs and antennae. In short, there is nothing hap- 
hazard about the way in which the militicida majors deal with their 
opponents; they only strike at parts which will put their opponents 
out of action or kill them. It is clear that their method is highly 
effective for it was only occasionally that the Pogonomyrmex workers 
got the better of the engagement. Even when they outnumbered the 
militicida majors they often failed to kill a single one of them and 
when they did so it was usually a result of the militicida major 
having been stung. This incapacitates them but does not immediatelv 
kill them. 
It should be clear that the activities just described are considera- 
bly more methodical that the ordinary scrimmages between fighting 
ants. In these activities the militicida major shows an efficiency that 
