Climate change and globalisation are favouring the arrival and spread of non-native ants. Some become invasive, disrupting native ecosystems and causing nuisances. Here is a status report on the species concerned in Europe.
Lasius neglectus: the silent invader
Native to Central Asia, Lasius neglectus was detected in Europe in the late 1990s. It looks a lot like Lasius niger (our native black ant), but differs from it by:
- Polygynous colonies (several queens, up to hundreds)
- An absence of nuptial flight (reproduction inside the nest)
- The formation of supercolonies with no inter-nest borders
- Strong aggressiveness towards native ants
Wherever it settles, it gradually eliminates other ant species and disrupts soil fauna. Supercolonies several kilometres long have been observed in European urban parks.
Lasius neglectus is one of the most concerning species for European urban and peri-urban ecosystems. Its spread is monitored by researchers at natural history museums.
Tapinoma magnum: the southern pavement ant
Native to North Africa, Tapinoma magnum appeared in southern Europe in the early 2010s and is advancing rapidly northward. It forms massive colonies along roads, in parks and urban areas.
Recognisable by:
- Small size (3-4 mm), dark brown
- Very aggressive territorial behaviour
- Formation of dense, continuous trails
- Presence in homes (kitchens, bathrooms) during warm spells
It displaces native Mediterranean species (Tetramorium, small Camponotus).
Linepithema humile: the Argentine ant
One of the most problematic worldwide. Linepithema humile was introduced to Europe in the early 20th century. It forms a single supercolony stretching from the Portuguese Atlantic coast to Italy, along the entire French Mediterranean coast. All the workers of this supercolony are genetically related and do not fight one another.
Consequences:
- Near-total disappearance of native ants in colonised areas
- Disruption of ecosystems (pollination, seed dispersal)
- Nuisance in urban areas (presence inside homes)
Solenopsis invicta: the future threat
The American fire ant is not yet established in mainland Europe, but it was detected in Sicily in 2023. Researchers fear its spread northward. If it settles in:
- Very painful stings, sometimes fatal for allergic people
- Massive economic cost (agricultural and electrical damage)
- Total disruption of native ecosystems
Monitoring it is a European priority.
Anoplolepis gracilipes: the yellow crazy ant
A tropical species detected occasionally in European greenhouses. Not established outdoors but kept under surveillance.
How to limit the spread?
Several behaviours can slow the invasion:
- Don’t move soil, potted plants or gardening materials between regions without precautions
- Inspect crates and pallets received from infested areas
- Report sightings on platforms such as GBIF or national biodiversity inventories
- For keepers: never release a captive-raised colony into the wild, even a local one (a genetic and health risk)
Keeping exotic species is regulated in many countries. The list of species whose keeping is banned is regularly updated by ministerial decree. Check before buying or collecting.
Citizen observation
Monitoring invasive ants relies partly on citizen reports. If you observe an unusually large or aggressive colony, or a species new to your region, you can report it via:
- National biodiversity inventory portals
- Specialist myrmecology forums
- Local entomological associations
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