With varying the overhead illumination during flight over large distances. This study has overcome this hurdle, atleast for honeybees, by using a tunnel to simulate a long journey, and manipulating the illumination in the tunnel. Earlier studies have shown that the waggle dances of bees returning from a food source can be systematically altered by illuminating the hive with artificially polarized light and varying the direction of polarization of this illumination [1,7]. These experiments are telling, in that they demonstrate that bees can perceive and react to polarization patterns, but such experiments are restricted to modifying behaviour within the hive. They do not reveal whether bees flying outdoors to a food source are able to gauge their flight direction purely from the pattern of polarization that is present in the sky. Observations of the ability of animals to orient spontaneously to e-vector patterns have been documented in a number of invertebrate species (e.g. locusts, shrimps, bees, etc. [25]). In one series of experiments, Jacobs-Jessen [26] showed that when foraging bees were captured and released from a hole in the centre of a circular table, which was LM22A-4 manufacturer illuminated from above with polarized light, the walking bees oriented their body axes in four different preferred directions relative to the e-vector of the illumination. While this experiment suggests that bees have the capacity to sense the direction of the e-vector, they do not indicate whether they use this information to measure or set their direction of flight when they fly towards a known food source. In another series of experiments, Jacobs-Jessen [26] HMPL-012 cancer arranged for bees to emerge from their hive through an aperture at the centre of a circular table (as above), with a horizontal sheet of glass positioned just above the table. This encouraged the bees to walk, rather than fly, to the periphery of the table before flying out through a specific exit. There were exit holes all around the periphery, but only one was open. He found that, when the experiment was carried out under the open sky, the bees learned to walk in the correct direction to find the exit hole. This was true regardless of whether the sun was visible, or screened off by a mask, allowing only a part of the remaining blue sky to be visible. While this elegant experiment demonstrates that the bees were using celestial cues to gauge and set their walking direction, it does not reveal the nature of the relevant cue–which could be the position of the sun, the polarization pattern of the sky, the intensity or spectral gradients in the sky, or a combination of all of these cues. Our experiments demonstrate that foraging bees can sense and signal the direction of their flight by using information that is based purely on the polarized-light pattern of the sky. It should be noted, however, that the polarization filters in our experiments provided a degree of polarization of around 95 , whereas the degree of polarization of natural skylight is somewhat lower, rarely exceeding 60 [2,27]. Experiment 1 has shown that bees can read a compass direction and report it in their dances when they fly in a tunnel under the open sky. However, this experiment on its own does not tell us whether the compass information is obtained from the sun, from the polarization pattern or from the other cues listed above. Experiments 2 and 3 address this question, by providing overhead illumination that contains only polarized-light cue.With varying the overhead illumination during flight over large distances. This study has overcome this hurdle, atleast for honeybees, by using a tunnel to simulate a long journey, and manipulating the illumination in the tunnel. Earlier studies have shown that the waggle dances of bees returning from a food source can be systematically altered by illuminating the hive with artificially polarized light and varying the direction of polarization of this illumination [1,7]. These experiments are telling, in that they demonstrate that bees can perceive and react to polarization patterns, but such experiments are restricted to modifying behaviour within the hive. They do not reveal whether bees flying outdoors to a food source are able to gauge their flight direction purely from the pattern of polarization that is present in the sky. Observations of the ability of animals to orient spontaneously to e-vector patterns have been documented in a number of invertebrate species (e.g. locusts, shrimps, bees, etc. [25]). In one series of experiments, Jacobs-Jessen [26] showed that when foraging bees were captured and released from a hole in the centre of a circular table, which was illuminated from above with polarized light, the walking bees oriented their body axes in four different preferred directions relative to the e-vector of the illumination. While this experiment suggests that bees have the capacity to sense the direction of the e-vector, they do not indicate whether they use this information to measure or set their direction of flight when they fly towards a known food source. In another series of experiments, Jacobs-Jessen [26] arranged for bees to emerge from their hive through an aperture at the centre of a circular table (as above), with a horizontal sheet of glass positioned just above the table. This encouraged the bees to walk, rather than fly, to the periphery of the table before flying out through a specific exit. There were exit holes all around the periphery, but only one was open. He found that, when the experiment was carried out under the open sky, the bees learned to walk in the correct direction to find the exit hole. This was true regardless of whether the sun was visible, or screened off by a mask, allowing only a part of the remaining blue sky to be visible. While this elegant experiment demonstrates that the bees were using celestial cues to gauge and set their walking direction, it does not reveal the nature of the relevant cue–which could be the position of the sun, the polarization pattern of the sky, the intensity or spectral gradients in the sky, or a combination of all of these cues. Our experiments demonstrate that foraging bees can sense and signal the direction of their flight by using information that is based purely on the polarized-light pattern of the sky. It should be noted, however, that the polarization filters in our experiments provided a degree of polarization of around 95 , whereas the degree of polarization of natural skylight is somewhat lower, rarely exceeding 60 [2,27]. Experiment 1 has shown that bees can read a compass direction and report it in their dances when they fly in a tunnel under the open sky. However, this experiment on its own does not tell us whether the compass information is obtained from the sun, from the polarization pattern or from the other cues listed above. Experiments 2 and 3 address this question, by providing overhead illumination that contains only polarized-light cue.