Antics with ants

One sunny afternoon in April of 2010 I was sitting in our backyard reading when I saw what I can only describe as a rather astonishing interaction between 2 ants and one human.

I was watching 2 medium size (1cm) orange and black ants presumably searching for food on our paved patio area. They were doing what appeared to be an unusual version of "follow-the-leader" in which the lead ant would move forward a few body lengths and then stop. It did not move forward again until the trailing ant caught up and seemed to lightly brush the lead ants' rear legs. This seemed to provide some sort of signal to the lead ant informing it to move forward again for a few more body lengths or so. At this stage the cycle repeated. The first moved forward in a straight line then stopped while the second ant would weave from side to side then come up and "start" the first ant up again.

After a few minutes I decided to interrupt the 2nd ant just after the lead ant had stopped ... i.e. intercept the 2nd ant so that it could not reach the 1st ant. Basically I wanted to see how long the 1st ant would wait there---transfixed.

In the first of several attempts my interceptions merely slowed down the 2nd ant's return to its "duty" because it would try to find the cause of the disturbance ... namely, me lightly touching it on the back legs ... for a while and then go back to the 1st ant.

During the ever increasing delays the first ant simply waited ... then the cycles started again once I left the 2nd ant in peace.

Finally I removed the 2nd ant by flicking it away so that it was over 1 metre away and had little chance of finding the lead ant. This left the lead ant in an amazing state. While at first it was immobile, waiting for its signal to move ... after a few minutes I discerned the slightest twitches of forward movement ... almost as if it was trying to break free of some sort of instructional command.

After about 5 minutes of this I found another ant (it may or may not have been the second one) and I coaxed it over to the first ant ... when they met head on the "spell" was broken and the 1st ant went on its way.

POSTSCRIPT : I was on a walk in Guthega when I described this two-ant interaction to the group. Preston then explained that this was a well-studied phenomenon called "tandem-running". The ants are in fact a master and an apprentice, however, contrary to my assumption the lead ant is the master while the trailing ant is the apprentice. The master is teaching the apprentice where the chemical trails are to food sources. No wonder the master was starting to twitch --- where had its trainee disappeared to?