Myrmecia pilosula: All About the Jack Jumper Ant

Nov 3

2 min read

Updated: 1 day ago

Myrmecia pilosula, the jack jumper, is a small bull ant with a big reputation. It is famous for jumping, for its painful sting and for being the main cause of ant venom allergy in Australia. Here is everything you need to know about the jack jumper.

Names

Myrmecia pilosula goes by many names: jack jumper, jumping jack, hopper ant, jumper ant, black jumper and skipper ant. It was described in 1858 by the British entomologist Frederick Smith from specimens collected in Hobart, Tasmania. The name pilosula comes from Latin and refers to its soft hairs.

Appearance

Workers are around 12 to 14 mm long, queens around 14 to 16 mm. The body is black or blackish red, while the legs, antennae and long jaws are yellow or orange.

Myrmecia pilosula, one of the smaller bull ants.

Where does it live?

The jack jumper is most common in Tasmania and southeastern mainland Australia, with dense populations in the Tasmanian mountains, the Snowy Mountains, the Blue Mountains and on Kangaroo Island. It prefers open habitats with gravel and sandy soil: open woodland, grassland, pastures, gardens and lawns, often at higher elevations.

Nest

Colonies build mounds of fine gravel, soil and pebbles, usually 20 to 60 cm across. The ants decorate and camouflage them with dry material, leaf litter and grass, which may help the nest catch the warmth of the sun.

Jack jumper worker (Myrmecia pilosula) with yellow jaws and legs — Myrmecia pilosula.

Jumping

Jack jumpers can leap 5 to 8 cm by suddenly stretching their legs. They are active during the day in the warmer months and rest in winter. With their good eyes, they follow intruders from around a metre away.

Colony life

A nest usually holds a few hundred to around a thousand ants. Many colonies have several queens that are not related to each other, and queens mate with several males. Queens can live for ten years or more, workers around one to one and a half years. Workers can also reproduce, even when a queen is present.

Venom and allergy

The venom contains special peptides called pilosulins. One of them is the main cause of jack jumper allergy, which affects up to about 3 percent of people in areas where the ant is common. Several deaths have been recorded in Tasmania, but since a desensitisation programme started in Hobart in 2003, no death has been officially recorded. Read more in jack jumper ant allergy.

One chromosome pair

The Myrmecia pilosula species complex is famous among geneticists: some of its members have just one pair of chromosomes, the lowest number possible for any animal. Read more in Myrmecia croslandi.