Asian honeybees sound a screamy alarm when murder hornets attack

Asian honeybees have been heard and recorded making a previously unknown sound, which is used to alert their hive mates to the presence of dangerous giant Asian hornets. 

Heather Mattila, an associate professor of biological sciences at Wellesley College in Massachusetts, described the noisy, high-pitched alarm call made by the Asian honeybee as an "antipredator pipe." Her new study found that its purpose is to alert other bees to the presence of the large attackers, which are sometimes known as murder hornets.

The much larger hornets either kill the bees or force them to abandon the nest, then feast on the larvae left behind. The bees' high-pitched alarm is a call to action of sorts. As the sound is made, the bees begin surrounding the entrance to the hive with animal dung to repel the giant hornets. Mattila reported on this behaviour — the first documented use of tools by bees — just last year. 

That buzzing noise means something...

The bees make sounds through the rapid vibration of the muscles in their thorax, which then transmit a vibration through anything it is standing on, such as another bee or even their hive. These alarm calls are different from any other sounds made by bees and increase regular hive chatter by as much as eight times.

The newly-discovered distress signal is similar to the attention grabbing shrieks and screams of fear made by some mammals and birds under threat. In an experiment, introducing the smell of murder hornets also triggered the bees to make the alarm sound.

Mattilla says the sounds can be heard both inside and outside a hive but seem to have no apparent influence on the behaviour of the hornets. 

Asian honey bees sound the alarm (Wellesley College)

When the bees produce the sound, they raise their abdomen, make their wings buzz, and expose a pheromone-producing gland. This behaviour may also be a signal to warn others. 

Produced and written by Mark Crawley.