Honey bees do a waggle dance to direct other bees to the sources of nectar. The dancing bees like this one can be halted by a headbutt from another bee. Now research has found that this headbutt is actually a warning signal. A feeding station was set up in the lab to mimic a source of nectar, then foraging bees were introduced to the dangers at the station, such as competition from rival colonies. When foragers returned to the hive they stopped bees dancing. Scientists think the behavior warns dancers of a dangerous source of nectar. Bees perform this strange ritual when they encounter aggressive rival bees, for example, or predatory spiders hanging out at favored foraging spots. When they return to the hive, they headbutt hive mates performing the famous “waggle dance” that directs would-be foragers to rich sources of nectar. By halting their hive mates mid-dance, the scouting bees save them from perilous excursions.