134 
Psyche 
[Vol. 89 
A. Intraspecific Field Experiment: Nasutitermes corniger 
Nasutitermes corniger (Motschulsky) is a common arboreal ter- 
mite ranging through much of Central and northern South America 
(Thorne, 1980). Large carton nests contain up to 800,000 termites 
(Thorne and Noirot, 1982) and, with the addition of foragers, total 
colony size may exceed a million individuals. Distinct foraging 
trails, covered by carton galleries, are visible issuing from a nest and 
proceeding along tree branches, trunks, and the ground surface. The 
termites also travel underground and in galleries located within trees^ 
or fallen logs. N. corniger foraging trails can radiate many meters 
from the parent colony. 
Given the density of N. corniger colonies in primary forest (7.0 ± 
1.8 per hectare in the Hubbell Plot of Barro Colorado Island, 
Panama, N = 4 hectares) and in areas of young second growth (27 in 
one hectare in Frijoles, Panama) (Thorne, unpub. data), it is likely 
that, at least occasionally, foraging parties from different colonies 
encounter one another in the midst of exploring or exploiting a local 
food source. Observation of a natural inter-colony encounter would 
be difficult. It would require tracking single foraging trails, which 
would undoubtedly result in disturbance as one cleared away the 
forest litter to locate foragers. Even if trails could be accurately 
followed without disruption, it would be rare to view simultaneous 
interception with an active trail known to be from a second colony. 
Because the odds of witnessing such a natural event are low, I forced 
an encounter through a transplant experiment. 
METHODS 
On the morning of 18 August, 1978 three Nasutitermes corniger 
nests were collected from separate areas of second growth near 
Sirena headquarters of Corcovado National Park, Osa Peninsula, 
Costa Rica. The nests measured 29.8, 52.7, and 41.9cm in height 
and 26.0, 29.8, and 26.0cm in diameter, respectively. Nests were 
sawed from their host trees and hand-carried to the experimental 
site. Each colony was suspended on a wire from one of two branches 
of a large tree (Fig. 1). The nests were hung in an equilateral triangle 
such that the distance from their base to the ground was 60cm, the 
distance from the edge of each colony to each neighbor was 50cm, 
and the original compass orientation of each colony was main- 
