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Psyche 
[Vol. 95 
branches and dead trunks of Cercidium floridum (blue palo verde) 
or C. microphyllum (little-leaf palo verde) were used as a source of 
termites even though H. aureus will utilize a variety of desert plants 
as hosts (Haverty and Nutting, 1975). The branches were brought 
back to the laboratory at the University of Arizona and the termites 
extracted from each branch. Each termite group from a single tree 
was maintained separately in a plastic shoe box lined with moist 
paper towels. 
Arenas 
Rectangular arenas were assembled for pairs of termites from two 
thin plastic strips and two machine nuts. The components were 
arranged so the plastic strips were adjacent to the machine nuts and 
the unit placed on paper to give the termites a “grip.” This con- 
struction made manipulation of arena size easy and deterred 
termite escape. Glass arenas were used for simulated foraging 
studies (Fig. 1). The arena dimensions were 17 X 21 X 1 cm and 
could accommodate approximately 1000 termites. 
Soldier and worker interactions: arena size 
Each soldier was placed in an arena and observed until its behav- 
ior stabilized. A soldier or worker from the same colony was intro- 
duced and the pair observed for 3 minutes. The added soldier or 
worker was removed and a soldier or worker from a different colony 
was placed in the arena with the same soldier for 3 minutes. Obser- 
vations for soldier/ soldier interactions were at a single arena size 
(1.5 cm 2 ) while soldier/ worker observations were made at 4 arena 
sizes (1.5, 3.0, 4.5, and 6.0 cm 2 ). Two replicates of 10 soldiers, each 
with 8 pairings of different workers, were completed for a total of 
160 observations. During the 3-minute period the number of snaps 
of the mandibles was recorded, the time to a fatal snap, the number 
of encounters, and any behavior that was consistent throughout the 
course of the experiment. 
Soldier vs. worker interactions: immobilization of soldiers 
or workers 
Termite aggression was investigated by immobilizing workers or 
soldiers between the head and the thorax with a small card with a 
V-shaped notch cut in the edge. The immobilization procedure in no 
way injured the animal, because normal behavior resumed when the 
card was lifted. In one experiment only the worker head was 
exposed to a freely moving soldier. In another, only the worker 
