Aggressive Ants
These Messor Ants are from the same nest. They were peacefully walking along a foraging trail when they were recruited for research. They attacked each other during the research work in the petri dish, and stayed locked in combat for a long time after they were put back on the ground near the nest. Perhaps there is an aggression switch or pheromone, which gets switched on, causing the ants to attack whatever is near ??