Myrmecia brevinoda is nocturnal and among the largest of the genus, with workers attaining lengths of up to 1.5 inches. Workers are solitary foragers, and Myrmecia spp. rely heavily on eyesight and do not leave pheromone trails. They have powerful stings, and some species in this genus have a high rate of causing anaphylactic reactions (for a hymenopteran, e.g. 2-3% of Tasmanian people are allergic to M. pilosula, making it one of the world’s most dangerous insects). Some studies suggest jack jumper ants have one of the most toxic insect venoms, and they can also emit alarm pheromones near the nest to swarm an intruder.
Common names: Myrmecia spp. are called jack jumper ants because some species jump when disturbed, and they are also called bulldog ants because of the tenacity they exhibit when tugging on prey with their large mandibles.