Food-deprived colonies were given access to a maze with a large 1 M sucrose solution feeder at the opposite end. The maze con- sisted of two parallel paths, 10 mm wide and 200 mm long, joined at each end by a 90 Y-bifurcation with 40 mm long arms (see Fig. 1), thus forming a stretched hexagon. The maze and all other parts of the apparatus to which the ants had access were covered in disposable paper overlays. Equal numbers of black glass beads, either uncoated (control beads) or coated with nestmate CHCs (dummy ants), were placed on both paths. The first 10 ants to reach the feeder were marked with a dot of acrylic paint on the abdomen, so as to allow the behaviour of individual ants to be followed on their first return trip to the nest. The ants were then allowed to forage undisturbed for 1 h, during which the entire maze was filmed in high definition from above using a Sony Handycam CX190. From these videos we obtained information such as the number of ants on each path at various times, the time at which the first ants began returning to the nest and the number of U-turns. At the end of the experiment all marked ants were removed from the colony, the remaining ants returned to the nestbox, the maze cleaned with ethanol and the paper overlays replaced. Both control beads and dummy ants were discarded after every trial.