Red Imported Fire Ant

Fast Facts

Latin name: Solenopsis invicta

Notable feature: Fire ants are quite small, varying from 2 - 6mm in length, and are predominantly reddish-brown in colour with a black gaster. The pedicel, or "waist" in the Red Imported Fire Ant consists of two segments. The mandible has four distinct teeth, and the antennae are 10-segmented.

Conservation Status: Not Evaluated

Where in the UK: Currently not found in the UK. Recent studies show that this ant species has become established in Italy and could rapidly spread through Europe to the UK with global warming. Researchers have concluded that it could establish itself in approximately 7% of Europe.

Red Imported Fire Ant (Solenopsis invicta) © Judy Gallagher (Flickr, CC)

The Red Imported Fire Ant (Solenopsisinvicta) is currently not recorded in the UK, if it were to be so it would be considered an Invasive Non-Native Species.

Red Imported Fire Ants are quite small, varying from 2 – 6mm in length, and are predominantly reddish-brown in colour with a black gaster (the rear most segment in the ant).  The pedicel, or “waist” in the Red Imported Fire Ant consists of two segments. The mandible has four distinct teeth, and the antennae are 10-segmented.

It is an aggressive generalist forager ant that occurs in high densities and can thus dominate most potential food sources. They breed and spread rapidly and, if disturbed, can relocate quickly to ensure survival of the colony. Their stinging ability allows them to subdue prey and repel even larger vertebrate competitors from resources.

Once in an area the Red Imported Fire Ant is almost impossible to eradicate but can be controlled.  It is a “hot climate specialist” and inhabits hot arid regions.

Researchers have estimated that half of the urban areas in Europe would be climatically suitable for it, including large cities such as London, Paris, Rome, and Barcelona. With increased temperatures caused by man-made climate change, the continent will become much more suitable for the species and help its spread across Europe.

    • Size: Approximately 2-6mm in length
    • Life span: The lifespan of Red Imported Fire Ant workers depends on their size. Minor workers may live 30 to 60 days, medium workers 60 to 90 days, major workers 90 to 180 days, and queens may live two to six years. Complete lifecycle from egg to adult takes between 22 and 38 days.
    • Diet: The Red Imported Fire Ant may feed on invertebrates, vertebrates and plants, and oily or sugary foods. However, it is known to prefer protein-rich food sources and may be a great consumer of insects, ticks, seeds, seedlings, young trees, plant buds, and fruits. 
    • Reproduction: The queen produces from 800 to 2000 eggs per day. She produces sterile worker females and occasionally fertile females and males. Fertilised females may start new colonies. Mating flights are the primary means of colony propagation, secondarily, budding can occur in which a portion of a colony becomes an autonomous unit 
    • When to see: Currently not found in the UK.  But in countries that the ant can be found they are most likely to thrive and spread in warm, well-connected regions.  Urban areas may also be suitable for the species to thrive due to their many heat sources, such as buildings. 
    • Population Trend:  Unknown
    • Threats:  The Red Imported Fire Ant is among the most damaging invasive insects on earth due to their aggressive nature and lack of natural enemies.
        • The Red Imported Fire Ant can rapidly form large colonies with multiple queens.
        • The ants prey on invertebrates, small vertebrates, and plants, destroying native plants and out-competing native species. 
        • Red Imported Fire Ants have been reported to reduce ground-nesting populations of rodents and birds. 
        • Stings from the Red Imported Fire Ants are an important public health concern. Stings may produce a large range of reactions from localized pain and swelling to anaphylactic shock, making it hard to estimate the cost to public health.
    • Fun Fact: The queen can produce up to 3,500 eggs per day which is about 9 million eggs in her life time of up to 6 years.  Each nest has one or more queen. A single colony may have 100,000 to 500,000 ants of various sizes and includes a queen, drones, and workers. The workers are sterile females. 
    • Additional Fun Fact: The Red Imported Fire Ant’s mound-building activities are sometimes considered to improve soil quality, e.g. by reducing soil compaction or increasing NH4+ levels.

How you can help: 

Buglife is working to increase awareness of invertebrates and the potential and real threats from non-native invasive species, but we need your help!

  • Report any unusual looking ants to Buglife. 
  • Buy locally grown plant species rather than imports. 
      • Buying locally grown plants, or bare-rooted plants is the best way to ensure we are not spreading non-native species. Plants should be regularly checked to ensure they are free from stowaways and garden centres should be following the Code of Practice to prevent the spread of non-native Flatworms. 
      • Alternatively, grow plants from seed or cuttings. See our Gardening for Bugs pages for more wildlife-friendly ideas. 
  • Sign our petition to stop the import of soils and products containing soils: 

Do remember that we rely on donations to continue our work.  If you have searched, found and learnt about our incredible invertebrates on our website, please do consider Making a DonationBecoming a Member or maybe even making a purchase in our shop.  For more ideas on how to support our work find out how to Get Involved.  Thank you 🕷