1988] 
Holldobler — Chemical communication 
141 
mately 50-60 workers. Although the queenless worker groups were 
found at least 50 m away from both queenright colonies, when they 
wer joined with a queenright colony, they readily merged without 
any sign of aggression or aversion. 
The first indication that Meranoplus communicates by chemical 
trails was obtained when I dumped a field-collected colony inside 
the arena where I also provided a dark, moist test-tube nest. The 
colony first gathered in clusters along the arena wall. A few workers 
explored the surroundings of the arena, until after 43 minutes the 
first scout discovered the test tube nest. A few minutes later 3 more 
workers entered the nest. When leaving the nest the workers clearly 
exhibited trailing behavior, tapping their gaster tips repeatedly to 
the gound and sometimes even dragging them on the floor for dis- 
tances of 0.5- 1.0 cm (Fig. 1). This behavior was especially conspicu- 
ous near the entrance of the nest tube. Subsequently, the number of 
workers moving toward the nest increased markedly, although no 
clear trail following could yet be noticed. However, after an addi- 
tional period of approximately 30 minutes, a continuous trail, lead- 
ing from the cluster of ants to the nest, began to be established (Fig. 
2a). Scouts, which returned from the newly discovered dark nest, 
Figure 1. A worker of Meranoplus hirsutus dragging its abdominal tip over the 
ground during trail marking. The arrow points to the extruded sting. 
