Four colonies of bees, divided into two pairs, were used for this test. Old workers (i.e. bees with darkly pigmented scutellum) were removed from one colony of the pair and individually placed in small vials (3.5 cm height 2.0 cm diameter) containing cerumen from supporting pillars of their own nest (ca. 2.0 cm 5.0 mm) or from the other nest. These bees were kept in the vial with the cerumen for either 10 or 20 min. The bees were then placed back in the experimental box of their own colony. We then noted the response of other bees to the introduced individual, as described above. We tested 30 bees from each experimental group.