386 
Psyche 
[December 
nest terrarium foraging arena 
Fig. 1. Laboratory nest arrangement, a — nest chambers; b = bridge; 
s — sand. 
(75 X 30 X 30 cm). These colonies had been kept in the insectary 
for three years, since the early spring of 1967. Their good health 
was attested by the fact that they continuously reared large quan- 
tities of brood, and each year produced winged males and females. 
Each nest terrarium was connected with a foraging arena 70 cm 
in diameter (Fig. 1). This combination provided an excellent ar- 
rangement for laboratory pheromone tests and orientation experi- 
ments that simulated natural conditions. Additional methodological 
details will be given with the description of the individual experi- 
ments. 
Experiments and Results 
Description of the food alarm behavior 
We have noted that when individual workers of P. badius attack 
large, active insect prey in the vicinity of the nest, they discharge the 
alarm pheromone 4-methyl-3-heptanone from their mandibular 
glands. The pheromone both attracts and excites other workers 
within distances of ten centimeters or so, with the result that the 
prey is more quickly subdued. This observation led to the question: 
Do workers also employ a directed food alarm when they encounter 
a food source several meters distant from the nest entrance? The 
following laboratory experiments were designed to find an answer 
to this question. 
In the center of the foraging arena (Fig. 1) a freshly killed 
cockroach ( Nauphoeta cinerea) was offered. The first ant to dis- 
cover the prey was marked ; all other scouting ants were then 
removed. After several unsuccessful attempts to transport the 
cockroach, the scout ant typically ran toward the arena exit near 
