1988] 
Holldobler — Chemical communication 
149 
To investigate whether these markings can serve as homing cues, 
the paper floor was placed into another arena and 20 ants, taken 
from the nest tube, were released in the new arena. In all five repli- 
cas of the same test, most of the displaced ants had gathered within 
15 minutes at the exact spot on the paper floor where the nest 
entrance was previously located (Fig. 5b). 
In a second series of tests the colony Meranoplus sp. no. 1 1 was 
transferred into a new arena with a new paper floor and two pieces 
of paper (5X5 cm) were placed approximately 5 cm from the nest 
entrance. The centers of both papers were approximately 10 cm 
apart. Papers marked by the test colony, by a conspecific foreign 
colony, by a colony of another Meranoplus species and unmarked 
papers were tested in different combinations (Tab. 3). Approxi- 
mately 40 ants were released into the arena, and subsequently the 
nest tube was removed. After an adjustment period of 15 to 20 
minutes, I counted the number of ants on each paper. At least one 
hour elapsed before another test was conducted and the left-right 
arrangement of the pairs of test papers was alternated from test to 
test to take into account possible artifactual preferences for one side 
or another. As can be seen from table 3 workers of Meranoplus sp. 
no. 1 1 appear to be able to differentiate the markings from their 
own colony from those of conspecific foreign colonies and colonies 
of other Meranoplus species. Interestingly, when encountering for- 
eign markings the ants did not exhibit a particular aggressive behav- 
ior or avoidance. This suggests that the markings do not function as 
territorial signposts, but rather as homing and colony recognition 
cues. 
Table 3. Number of ants of the test colony ( Meranoplus sp. no. 11) counted on 
papers marked by different Meranoplus colonies. The means of 7 experiments and 
standard deviations are given. 
Test colony vs unmarked paper 
6.57 ±2.51 0.71 ±0.95 
Test colony vs foreign conspecific colony 
9.00 ± 2.94 1.43 ± 1.27 
Test colony vs colony of Meranoplus hirsutus 
8.14 ± 3.72 1.43 ±2.15 
