Tropical fire ant


harms crops

harms people

harms wildlife

lives on ground

day active

night active

different sizes

Scientific name: Solenopsis geminata

Other common name: ginger ant

Size: 3-8 mm

Colour: orange to reddish brown

General description: workers of this ant come in a wide range of sizes (polymorphic), the larger majors have very square heads. Unlike the red imported fire ant, the tropical fire ant does not build mounds, instead, dirt is spread widely around the nest entrance. It can be difficult to identify the difference between red imported fire ants and tropical fire ants. Red imported fire ants are much more aggressive their stings are more painful and result in blisters after 24 hours.

Habitat and nesting: the tropical fire ant is a ground/ soil dwelling species that typically colonises open disturbed environments. The ant tends to avoid nesting in shaded areas and the forest interior.

Rate of spread: rapid, but unspecified.

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


Tropical fire ant majors have large, square heads (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA License)

Tropical fire ants come in a wide range of sizes (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA License)

Reproduction: tropical fire ants are a bit different from most other species of invasive ants. They can form two types of colony, technically called polygyne or monogyne.

Polygyne colonies have multiple queens. These colonies spread mostly by budding, like the other "worst 5". Sometimes mating flights can occur but they do not fly far. 

Monogyne colonies have a single queen and live in only one nest. They have mating flights, where new queens fly up to 2 km from the nest they were born in to form new colonies. These mating flights make the monogyne form of the red imported fire ant much more difficult to contain.

For detailed descriptions and identification of tropical fire ants:

PIAkey: Solenopsis geminata (see diagnostic characters tab)

AntWeb: Solenopsis geminata

Video of tropical fire ants on sugar bait, Vimeo video (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA License)
Video of tropical fire ants foraging on a tree in Hawaii, Vimeo video (© Eli Sarnat, Creative Commons Attribution, Share Alike CC BY-SA License)

Social, agricultural and environmental impacts of the tropical fire ant

Though the tropical fire ant is less aggressive than the red imported fire ant, it will still readily sting people that disturb its nest. Its sting is very painful and raises red itchy bumps that last for days.

This ant can be a significant agricultural pest: it forms associations with sap-sucking insects and protects them from predators which can lead to reductions in plant productivity and outbreaks of crop pests and disease (which is carried by the pests).

Tropical fire ants can interfere with harvesting by stinging agricultural workers. Workers chew holes through irrigation hoses.

Tropical fire ant major worker (© Alex WIld)

The ant has been known to feed on seeds and seedlings a large variety of crops, causing a lot of damage.

Tropical fire ants kill hatchling turtles, eat the eggs of birds and reptiles and injure nestling seabirds, reducing their survival.


If you are interested in getting rid of tropical fire ants, have a look at the management programme case study for this species to see an example of a control programme that targets them.

Information sources

AntWiki, Tropical fire ant

Biosecurity New Zealand Invasive Ant Threat Information Sheet number 24, Tropical fire ant

ECOS - Science for Sustainability - CSIRO blog, Tropical fire ant,

Global Invasive Species Database (GISD)

Global Register of Introduced and Invasive Species (GRIIS)

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

PIAkey, Tropical fire ant

Plentovich, Hebshi, Conant. 2009. Detrimental effects of two widespread invasive ant species on weight and survival of colonial nesting seabirds in the Hawaiian Islands. Biological Invasions 11: 289-298

Content reviewed by Eli Sarnat, Antwork Consulting, LLC, June 2017

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