Mutillidae durable, the exoskeleton is also round, making it more difficult for predators to pierce it with attempted stings or bites. During all the trials that led to the fracture of a velvet ant’s exoskeleton, a total of 4 times, resulted in the death of that velvet ant within 24 hours. Thus aside from protection from predators, the exoskeleton provides a function maintaining moisture control. Male mutillids fly in search of females; after mating, the female enters a host insect nest, typically a ground-nesting bee or wasp burrow, and deposits one egg near each larva or pupa. Only a few species
Jack jumper ant in his "Catalogue of hymenopterous insects in the collection of the British Museum part VI", under the binomial name "Myrmecia pilosula" from specimens he collected in Hobart in Tasmania. There, Smith described the specimens of a worker, queen and male. The type specimen is located in the British Museum in London. In 1922, American entomologist William Morton Wheeler established the subgenus "Halmamyrmecia" characterised by its jumping behaviour, of which the jack jumper ant was designated as the type species. However, John Clark later synonymised "Halmamyrmecia" under the subgenus "Promyrmecia" in 1927 and placed the ant in the subgenus in 1943.