The ants are almost impossible to distinguish from the common black garden ant, although they behave very differently: queens live underground, mating within the existing colony rather than flying to a new one, so Lasius colonies can grow extremely large. They are also known for their attraction to sources of electricity, which stimulates them to produce a pheromone. This then brings in other ants in large numbers, occasionally causing blackouts and fires. They are otherwise not harmful to humans.
The RHS Advisory Service says gardeners should not be alarmed, as the new ants are unlikely to be any more damaging to garden plants than native ants. However, it is possible that if the new species starts appearing more widely, their habit of forming super-colonies across wide areas could mean they out-compete native ant species for food resources and reduce garden biodiversity.
“The Hidcote colony may be an isolated introduction, possibly brought in amongst the roots of an imported plant,” says principal entomologist Andrew Halstead. “But the ant is now established in several countries on the mainland of Europe, so it is likely that there could be further introductions into Britain with nursery stock.”
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