Argentine Ant

The Argentine Ant (Linepithema humile ) has been recorded in the UK but is not established; with nests being destroyed once reported.  If it were to establish it would be considered an Invasive Non-Native Species.

The Argentine Ant is a small to medium-sized ant, ranging from 2-3 mm in length.  Argentine Ant workers are monomorphic, displaying no physical differentiation. The workers of this species are dark brown in colour.  They have a smooth, shiny body surface, lacking hairs on the dorsum of the head and thorax.  The petiole is composed of a single, scale-like segment, and sting is absent.

Their eggs are pearly white, elliptical in shape and about 0.3 mm long.

Widely distributed in Western Europe following introduction in the 1800s. In the UK, there have been records since 1927; however, all have been indoors except one population in Fulham, West London, discovered in 2016; future establishments are likely.

Climatically, there are several sites within the UK that are suitable for establishment of Argentine Ant populations; the number of expected areas likely to increase under climate change.

The Argentine Ant invades sub-tropical and temperate regions and is established on six continents. Introduced populations exhibit a different genetic and social makeup that confers a higher level of invasiveness (due to an increase in co-operation between workers in the colony). This allows the formation of fast-growing, high-density colonies, which place huge pressures on native ecosystems.

• Size: Argentine Ants range from 2-3mm in length.
• Life span: The lifespan of Argentine Ants depends on their size and purpose within the colony. Males typically live a few days to a month or two after reaching adulthood, and usually die shortly after mating; those that participate in a nuptial fight tend to live longer. Most queens are executed in the spring by workers at the age of 10-12 months and replaced by newly mated queens. Queens that aren’t executed can live for over a year, likely several years. Workers live for about 10 to 12 months.
• Diet: Studies suggest that Argentine Ants use carbohydrate-rich resources such as honey.  The ant has an overall generalised diet (similar to other invasive ants), including nectar, insects, carrion and honeydew secreted by aphids. Their diet can change overtime with newly established colonies tending to feed on protein-rich insect prey, while long-established super colonies primarily consume carbohydrate-rich honeydew.
• Reproduction: Although the workers of all invasive ants are sterile, the Argentine Ant can rear eggs. Virgin queens are believed to mate in the nest and disperse through budding rather than participating in a nuptial flight, resulting in the formation of large, many-queened, cooperating colonies. Queens may be killed by workers after one year and replaced by newly mated queens.  Sexual reproduction of workers and females (typical form of reproduction) and males by parthenogenesis; males and females can reproduce independently by cloning, and workers reproduce sexually. Cloning is typically observed in human or disturbed habitats, whereas sexual populations typically occur in natural habitats.
• When to see: As this ant is not established in the UK, with nests being destroyed once reported, it is difficult to say where it can be found and seen.  Argentine Ants thrive in a Mediterranean climate where winters are cool and wet and summers are warm and dry. When conditions are ideal, they largely keep to themselves, but when conditions are drought-like or extremely wet, the ants move indoors in search of more hospitable climes
• Population Trend:  Unknown
• Threats: The Argentine Ant has been listed as one of the 100 most invasive species in the world by “Invasive Species Specialist Group of the World Conservation Union (IUCN)”.
  • • Several characteristics contribute to its invasive success in new environments: they can displace native ant species and attack other invertebrates. Argentine ants out-compete native species because they find food sources faster, forage longer, quickly recruit larger number of food sources, and function in a large range of habitats.
    • Loss of native invertebrates can have important knock-on impacts within ecosystems. In displacing native ant species, Argentine Ants disrupt many ant-plant seed dispersal mutualisms, and do not appear to disperse seeds themselves.
    • Could cause negative impacts on crops due to mutualistic relationships with other invertebrates.
    • Does not bite humans, but could be a nuisance in homes, particularly as colonies grow rapidly and reach large number.
• Fun (?) Fact: A mass execution of Argentine Ant queens takes place every spring.  Each spring, just before mating season begins, worker ants go on a killing rampage and assassinate 90 percent of their queens.

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:

https://you.38degrees.org.uk/petitions/stop-importing-invasive-species

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 Donation, Becoming 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 🕷

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