Meet Trigona hyalinata, an aggressive, 10-toothed, highly suicidal bee. Its stinger is vestigial and has lost its defensive function, but this angry and altruistic bee doesn't let that hold it back.

Stingless bees are closely related to their better-known cousins, the honeybees, which sacrifice their lives when they sting animals that pose a threat to the hive. When a honeybee deploys its sting, it self-amputates, causing lethal injury. Although stingless bees have lost this heroic ability, they still suffer predation and attack from animals ranging from anteaters to other bees – and have taken to biting instead.

"Bees are at their most aggressive when defending their colony," says Kyle Shackleton of the University of Sussex, in Brighton, UK. The nest takes months to make, contains all the colony's food stores, the queen, and all of an individual bee's siblings. "If their colony dies, they have nothing."

Defensive behaviours are well known in social insects, which share a high degree of genetic relatedness and act altruistically for the good of the hive or colony.

Now Shackleton, working with Francis Ratnieks, also of the University of Sussex, and colleagues, have identified a new self-sacrificial behaviour in these stingless bees – biting to the point of suicide.