Myrmecia inquilina is a species of ant endemic to Australia in the subfamily Myrmeciinae, first discovered in 1955 and described by Athol Douglas and William Brown Jr. in 1959.

During the time of its discovery, Douglas and Brown announced M. inquilina as the first social parasite among the primitive subfamilies, and today it is one of the two known Myrmecia species to have no worker caste.

Due to its restricted distribution and threats to its habitat, the ant is "vulnerable" according to the IUCN Red List.

[2] Brown collected the first specimens in 1955 from large fallen trees in Western Australia, and it was officially announced as the first parasitic ant among the primitive subfamilies in 1956.

[3] In 1959, Australian naturalist Athol Douglas and American entomologist William Brown Jr. provided the first description of the ant in an Insectes Sociaux journal article.

[4] Brown discovered the holotype female from an M. vindex nest on 23 March 1955 northwest from Wagin at Badjanning Rocks, Western Australia.

The antennae are morphologically similar to M. vindex, but it is smaller in comparison; the petiole node is also longer and wider.

The pubescence is greyish in colour, and it is shorter and more noticeable on the clypeus and appendages while it is conspicuous on the postpetiole and gaster.

[2] The colour of the head and gaster are black, shading into reddish brown on the clypeus and around the frontal carinae.

[2] Myrmecia inquilina is only found in the south-west of Western Australia, with the holotype collected 225 kilometres (140 miles) from Perth.

[2] M. inquilina occurs in colonies with M. vindex and M. nigriceps, found in soil, under logs and flat rocks in woodland.

Observations show that the alates will climb up onto objects such as lighted fluorescent lamps and begin to fly after half an hour of endless running.