Little fire ant

stings
 

harms crops
 

harms people
 

harms wildlife
 

lives in trees
 

lives on ground
 

day active

Scientific name: Wasmannia auropunctata

Other common name: electric ant

Size: 1.5 mm

Colour: light orange

Close up of a little fire ant worker (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA Licence)
 

Little fire ants swarming on a rock (© Forest and Kim Starr, Plants of Hawaii)

General description: this is a very tiny ant! To the unaided eye, it will just appear as a moving orange dot. This ant forms 3-dimensional colonies (on ground and covering vegetation including large trees).

Habitat and nesting: little fire ants nest in trees and on the ground, particularly in disturbed environments. Nests may be found in spaces between plants and soil, under piles of leaves, in leaf axils, under stones or in rotten logs, under rubbish, in tree crotches and clumps of grass. The little fire ant has also been found nesting in floating vegetation and logs during floods.

Rate of spread: 73 m/year in Gabon, 170-500 m/year in the Galapagos depending on rainfall.

Distribution: see our invasive ant distributions page for the worldwide distribution of the little fire ant.

Reproduction: little fire ants have two types of reproduction. Clonal reproduction (i.e. the offspring are identical to the parents and sexual reproduction does not occur) is found in some populations, while other populations reproduce sexually. As clonal populations of this ant are more prevalent in the introduced range, this reproductive mode may contribute to invasion success. In Wallis and Futuna, non-clonal populations of little fire ant have declined substantially.

Development: little fire ants have a shorter development time than some of the other worst 5 invasive ants. Eggs take 8-10 days to hatch into larvae. Larvae develop for 16-18 days before becoming a pupae. Workers remain pupae for 11-12 days, then emerge as adults.

Little fire ants foraging on peanut butter in the Solomon Islands, Vimeo video (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA Licence)
 
Little fire ants foraging in Hawaii, Vimeo video. Note that unlike the other video, the scale bar on the left is in millimetres. That is how tiny these ants are! (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA Licence)

For detailed descriptions and identification of little fire ants please see:

PIAkey: Wasmannia auropunctata (see diagnostic characters tab)

AntWeb: Wasmannia auropunctata

Little fire ant workers surrounding their much larger queen (© Alex Wild)
 

Little fire ant workers are tiny! (© Alex Wild)

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Impacts of the little fire ant

Social

As well as nesting outside, the little fire ant also nests indoors, allowing it to sting people in their homes. Though the sting of little fire ants is very unpleasant for adults, it is much more painful for children and causes a very itchy rash, which may become infected if scratched.

Little fire ants form 3-dimensional colonies (on ground and covering vegetation including large trees). Little fire ants are easily dislodged from the canopy by a light breeze or people brushing past vegetation and tend to rain down on, and sting, those walking beneath. This has been described as a “stinging rain”.

A little fire ant biting a person’s arm (© Plegadis, Wikipedia)
 

Little fire ant stings are especially painful to children (© Panya Kuanun / Shutterstock)

Agricultural

Not only does this ant tend to and cause outbreaks of sap-sucking insects, its painful sting can make harvesting crops in gardens or on farms in infested areas almost impossible.

Little fire ants have been linked to tropical keratopathy, or corneal clouding, which has a negative effect on vision. In little fire ant infested areas there is a much higher incidence of blindness in livestock and pets.

In Tahiti the effects of this ant are so extreme that people have abandoned their land due to infestations.

 
Little fire ants in Hawai'i and French Polynesia, YouTube video (© Maui Invasive Species Committee)

Coffee plantations in the Galapagos have been completely abandoned to little fire ants. It is extremely painful for workers to gather the pods by hand due to the stinging ants and some plantations find it too unprofitable to pay workers the increased wages they would require to work under such conditions.

A domestic pig blinded by little fire ants in Yangoru, PNG (© Cas Vanderwoude)
 

Blind cat in a little fire ant infested area in Hawaii (© Cas Vanderwoude)

Environmental

In little fire ant infested areas, almost no other animals can live.

The ants sting and eat anything that can’t escape, including animals like geckos, baby birds and other invertebrates. On the Galapagos Islands, these ants kill and eat baby tortoises and attack the vulnerable areas on the adults.

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Management

The most important first step in reducing the potential impacts of little fire ants is effective movement controls.

Little fire ants are very often spread in nursery plants, so great care must be taken to avoid sourcing plants from little fire ant infested areas. Little fire ants are also easily spread through movement of waste, in particular green waste. A whole fire ant nest can be transported in a single Macadamia nut!

If you are interested in getting rid of little fire 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

Aoki, Hara, Niino-DuPonte, Cabral, Zarders. 2013. Little fire ant. University of Hawai'i at Manoa, CTAHR, Komohana Research and Extension Center

Biosecurity New Zealand Invasive Ant Threat Information Sheet number 39, Little fire ant

Entomology Today, Little fire ants on Guam

Foucaud, Orivel, Loiseau, Delabie, Jourdan, Konghouleux, Vonshak, Tindo, Mercier, Fresneau, Mikissa, McGlynn, Mikheyev, Oettler, Estoup. 2010. Worldwide invasion by the little fire ant: routes of introduction and eco-evolutionary pathways. Evolutionary Applications 3, 363-374

Fournier, Estoup, Orivel, Foucaud, Jourdan, Breton,Keller. 2005. Clonal reproduction by males and females in the little fire ant. Nature 435, 1230-1234

Global Invasive Species Database, Little fire ant

Global Register of Introduced and Invasive Species (GRIIS)

Harris, Abbott, Lester. 2005. Invasive ant risk assessment: Wasmannia auropunctata. Landcare Research and Biosecurity New Zealand

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

Island Biodiversity and Invasive Species Database (IBIS)

Vanderwoude, Montgomery, Forester, Hensley, Adachi. 2015. The history of little fire ant Wasmannia auropunctata Roger in the Hawaiian Islands: spread, control, and local eradication. Proceedings of the Hawaiian Entomological Society 48: 39-50

Walsh, Henschel, Abernethy, Tutin, Telfer, Lahm. 2004. Logging speeds little fire ant invasion of Africa. Biotropica 36(4): 637-641

Wetterer and Porter. 2003. The little fire ant, Wasmannia auropunctata: distribution, impact and control. Sociobiology 41(3): 1-41

William, Whelan. 1992. Bait attraction of the introduced pest ant, Wasmannia auropunctata (Hymenoptera: Formicidae) in the Galapagos Islands. Journal of Entomological Science 27(1): 29-34

 

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