40 
Psyche 
[Vol. 94 
nest contained within a 61 X 43 X 10 cm plywood box. The nest 
consisted of a plastic box filled with moistened dirt inserted into a 
larger plywood box and having a single entrance/ exit hole. A sim- 
ilar entrance/ exit hole from the plywood box to the outside was 
closed with a plastic plug which could be removed to allow raiding 
to occur. The lid of the plywood box was removable to allow exam- 
ination of the nest and the acitivity of P. lucidus workers prior to 
raiding. A cardboard cover was placed over the plastic nest box to 
prevent disturbing the colony when the lid was lifted, and was 
removed only when the interior of the nest was examined. 
Experience has shown that very large colonies of P. lucidus are 
able to make multiple raids in a single day (Sanwald, unpublished 
observations). To maximize the frequency of raids for this study, 
each colony was expanded, prior to the beginning of the experi- 
ment, by the addition of slave-makers and slaves of the appropriate 
species. The colonies were expanded until each included approxi- 
mately 1300 raiders and 4000 slaves at the beginning of the raiding 
season. Normal colonies usually contain several hundred slave- 
makers and slavs. This mixing procedure was possible because P. 
lucidus workers and slaves from different colonies can be success- 
fully mixed when they are from colonies containing the same slave 
species (Goodloe & Sanwald, unpublished data). Such mixes 
between any combination of adult slaves and slave-makers from 
colonies using different slave species have been impossible to 
achieve. 
Initially, each colony contained a single P. lucidus queen. The 
artificial colonies were kept indoors and observed until larvae 
appeared in the nest, from which time the colonies were allowed 
opportunities to raid. 
A fixed location was chosen on the two-acre site from which raids 
were allowed to occur. On every day when weather was favorable 
for raiding, between 1300 and 1400 hr, one of the colonies was 
brought outside and placed at this location. The plug was removed 
to allow passage in and out of the artificial nest. To prevent slaves 
from initiating an emigration out of the artificial nest, all emerging 
slaves were retrieved by hand and returned to the artificial nest at 
the end of the day. All P. lucidus workers, by contrast, were allowed 
to pass in and out so that raids could occur. 
Observations were made until the raiders had returned from any 
raids that occurred and activity of the slave-makers in and out of the 
