Yellow crazy ant

sprays acid

harms crops

harms people

harms wildlife

lives in trees

lives on ground

night active

day active

Scientific name: Anoplolepis gracilipes

Other common name: long-legged ant

Size: about 5 mm

Colour: yellow-orange, with a darker brown abdomen

General description: the yellow crazy ant is one of the largest invasive ant species. It is thin and has very long legs and antennae. It gets its name of "crazy" ant by its extremely fast, frantic movements. Workers all look the same (monomorphic).

Habitat and nesting: the yellow crazy ant is a ground or tree dwelling species that may also be found in walls, posts or other elevated habitats. The ant can be found in urban structures, grassland, woodland or rainforest. Nests may be found under leaf litter, piles of rubbish, in discarded coconut husks, in tree stumps, crab burrows and cracks in soil. The yellow crazy ant is not typically found in elevations above 1200m.

Rate of spread: 37-402 m/year in the Seychelles, to 1100 m/year on Christmas Island!

Close up of yellow crazy ant worker (© Alex Wild)

Yellow crazy ant workers (© Phil Lester)

Yellow crazy ants foraging on the forest floor, Queensland (© Wet Tropics Images)

Yellow crazy ant worker (left) and queen (right) (© Phil Lester)

Distribution: see our invasive ant distributions page for the worldwide distribution of the yellow crazy ant.

Global distribution of the yellow crazy ant (© Pacific Biosecurity)

Reproduction: although winged queens are seen flying, reproduction is most likely by budding (sometimes by a queen without any workers). 

Development: eggs take 18-20 days to hatch into larvae. Larvae develop for 6-20 days before becoming pupae. Worker pupae develop for about 20 days, queens for 30-34 days, before emerging as adults.

For detailed descriptions and identification of yellow crazy ants please see:

PIAkey: Anoplolepis gracilipes (see diagnostic character tab)

AntWeb: Anoplolepis gracilipes

Yellow crazy ants foraging on a sugar bait in Fiji, Vimeo video (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA Licence)

 Yellow crazy ants foraging in Hawaii, Vimeo video (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA Licence)

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Impacts of the yellow crazy ant


Yellow crazy ants move very fast and are active almost 24 hours a day.

In infested areas where they are in high abundances they can make daily life and sleeping difficult, as people have the ants running over them day and night.

In the Wet Tropics in northern Queensland, Australia, yellow crazy ants temporarily blinded a farmer after spraying acid in his eyes as he slept. His dogs were also temporarily blinded.

Similar reports of livestock being blinded by yellow crazy ants are also known from the Seychelles.

Yellow crazy ants may also nest in electrical equipment, causing break-downs and extensive damage.

On Tokelau, population explosions of the ant have severely affected people's lifestyles.


The people of Atafu talk about how the yellow crazy ants affect them, YouTube video (© PIAT, Pacific Biosecurity)

Les fourmis folles jaunes ont envahi Tokelau, YouTube video (© PIAT, Pacific Biosecurity)
Acid burns from yellow crazy ant spray (© Meghan Cooling)
Yellow crazy ants can cause electrical equipment to short out (© Jamie Naylor)


Yellow crazy ant workers farm sap-sucking insects (they protect them and eat the honeydew they produce) like aphids, scale insects and mealybugs, often causing outbreaks of these pests.

These insect outbreaks can lead to the death of the plant and the spread of diseases such as sooty mold.The sap-sucking insects can also carry and spread plant viruses.

In Australia, the ants build their nests at the base of sugar cane, loosening the soil around the roots and causing the plants to fall over, ruining the crop.


Yellow crazy ants affect sugar cane, YouTube video (© Invasive Species Council, Australia)
Yellow crazy ants farming aphids (© Department of Agriculture and Food, Australia)
Yellow crazy ants tending sugarcane scale (© Wet Tropics Images)


Since 1990, yellow crazy ants have been responsible for the death of 10-20 million red land crabs on Christmas Island, Indian Ocean. They readily kill and eat other crab species as well. The relationship between the yellow crazy ant and a invasive scale insect has devastated parts of the Christmas Island environment.

The ants can temporarily blind nesting seabirds and injure chicks.

They are particularly dangerous to young animals, such as small mammals, reptiles, amphibians and hatchling birds.

Yellow crazy ants threaten Christmas island Crabs (video begins talking about yellow crazy ants at 06 min 30 sec), YouTube video (© Luze Howe)
Yellow crazy ants dragging away a dead gecko (Dinakarr, Wikipedia)
Yellow crazy ants attacking a hermit crab (© Kirsti Abbott)

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If you are interested in getting rid of yellow crazy ants, check out the treatment options for this species, or look at management programme case studies to see examples of other control programmes that target them.

Information sources

Biosecurity New Zealand Invasive Ant Threat Information Sheet, Yellow crazy ant

Global Invasive Species Database, Yellow crazy ant

Global Register of Introduced and Invasive Species (GRIIS)

Gruber, Pierce, Burne, Naseri-Sale, Lester. 2018. Using community engagement and biodiversity surveys to inform decisions to control invasive species: a case study of yellow crazy ants in Atafu, Tokelau. Pacific Conservation Biology, in press.

Haines, Haines. 1978. Colony structure, seasonality and food requirements of the crazy ant, Anoplolepis longipes (Jerd.), in the Seychelles. Ecological Entomology 3: 109-118

Holway, Lach, Suarez, Tsutsui and Case. 2002. The causes and consequences of ant invasions. Annual Review of Ecology, Evolution, and Systematics 33: 181-233

Invasive Species Council, Yellow crazy ants in Cairns, Australia

Island Biodiversity and Invasive Species Database (IBIS)

Ito, Asfiya, Kojima. 2016. Discovery of independent-founding solitary queens in the yellow crazy ant Anoplolepis gracilipes in East Java, Indonesia (Hymenoptera: Formicidae). Entomological Science DOI: 10.1111/ens.12198

Lach, Hoskin. 2015. Too much to lose: yellow crazy ants in the Wet Tropics. Wildlife Australia Spring 2015: 37-41

Lester, Tavite. 2004. Long-legged ants, Anoplolepis gracilipes (Hymenoptera: Formicidae), have invaded Tokelau, changing composition and dynamics of ant and invertebrate communities. Pacific Science 58, 391-401

O'Dowd, Green, Lake. 1999. Status, impact, and recommendations for research and management of exotic invasive ants in Christmas Island National Park. Report to Environment Australia

Plentovich, Russell, Camacho. 2012. The effects of yellow crazy ant (Anoplolepis gracilipes) invasion and subsequent control on burrow-nesting seabirds in the Hawaiian archipelago. 20th Annual Hawai’i Conservation Conference (Talk)

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