By Matt Walker of BBC Earth News:
It is rare for any species of animal to regularly kill its own in combat. However, male Dawson’s bees, one of the world’s largest bee species, are so aggressive that they kill each other en masse in a bid to mate with females.
The bees enter a frenzy of fighting, and by the time their deadly combat is over, every male bee is either killed or has perished. The extreme behaviour, which can lead to even females being killed, is caught on film by a BBC natural history crew.
Video on BBC Earth News