Collective orientation in night-flying insects

SEVERAL investigations have been made using microwave radar techniques to study individual insects in free flight1–5. One of the most surprising claims to result from these studies is that insects flying at night sometimes adopt a common orientation, usually downwind1,2,4. This would imply a remarkable ability to determine wind direction when flying in conditions of severely limited visibility1. We report here an instance of collective insect orientation in nocturnal flight, although in this case, the direction of flight was against the wind.