[5] It is on a list of "one hundred of the world's worst invasive species" formulated by the International Union for Conservation of Nature (IUCN),[6] having invaded ecosystems from Hawaii to the Seychelles, and formed supercolonies on Christmas Island in the Indian Ocean.

The yellow crazy ant's natural habitats are the moist tropical lowlands of Southeast Asia, and surrounding areas and islands in the Indian and Pacific Oceans.

Because yellow crazy ants have generalized nesting habits, they are able to disperse via trucks, boats and other forms of human transport.

[1] Crazy ant colonies naturally disperse through "budding", i.e. when mated queens and workers leave the nest to establish a new one, and only rarely through flight via female winged reproductive forms.

[11] A survey on Christmas Island, however, yielded an average spreading speed of 3 meters (9.8 ft) per day, the equivalent of one kilometer (0.6 mile) per year.

They have been reported to attack and dismember invertebrates such as small isopods, myriapods, molluscs, arachnids, land crabs, earthworms and insects.

[13] Like all ants, A gracilipes requires a protein-rich food source for the queen to lay eggs and carbohydrates as energy for the workers.

[14][15] Crazy ants obtain much of their food requirements from scale insects, which are plant pests that feed on sap of trees and release honeydew, a sugary liquid.

[16] Experiments have shown that this connection is so strong that, in environments where A. gracilipes was removed, the density of scale insects dropped by 67% within 11 weeks, and to zero after 12 months.

[17] In Australia, yellow crazy ants have been found at more than 30 sites in Queensland, and in Arnhem Land in the Northern Territory, where a large scattered population exists.

[18] A single New South Wales infestation was detected and eradicated, and, in Western Australia, yellow crazy ants have been intercepted in shipping freight arriving at Fremantle.

[19][7] The crazy ant has a significant destructive impact on the island's ecosystem, killing and displacing crabs on the forest floor.

One of the most noticeable changes in the forest is the increased numbers of the stinging tree Dendrocnide peltata, which now flourishes in many areas frequently visited by humans.

The forest canopy also changed as the scale insects tended by yellow crazy ants multiplied and killed mature trees.

With help from the Christmas Island Crazy Ant Scientific Advisory Panel and support from the Australian Government they are holding ground.

The single massive colony was found to occupy nearly a quarter of the island, with up to 1,000 queens in a plot of land 6 metres (20 ft) wide.

While baiting has slowed the decline of the red crab, its effects on the crazy ant populations are only temporary, as escaping colonies invade the treated areas again, and it is expensive, requiring much man power.

In an effort to find a better control, after research, Australian Parks in December 2016 imported Tachardiaephagus somervillei, a small (2 millimetres (5⁄64 in)) wasp and began breeding them for release.

Further, restricting access to honeydew, by binding trees where the scale insects feed, dramatically reduced the colony as ant activity on the ground fell by 95% in just four weeks.

There are at least a dozen honeydew producing insects as well as extrafloral nectar from native acacia trees, all of which fuel yellow crazy ants.