The Tapinoma Magnum, a “very invasive ant that makes everyday life difficult”

In recent years, a new species of ants has ruined the life of some 200 homes in a neighborhood in the city of Saumur (Maine-et-Loire). This invasive alien species, called Tapinoma Magnum, proliferated again this summer, thanks to the high temperatures. Who are these insects and can we defeat them? The point with a specialist, Loïc Bidault, elected in ecology, sustainable development and energy transition in the city of Saumur who also holds the position of vice president of the Conservatory of natural spaces of Pays-de-la-Loire.

Loïc Bidault, elected ecologist of the city of Saumur and vice president of the Pays-de-la-Loire Natural Areas Conservatory. – Loic Bidault

can you show us the Tapinoma Magmo ?

It is a Mediterranean species, Corsican more precisely, which later arrived in the south of France. It has been with us, in Saumur, for three to six years, but we actually identified it last year, after protests from the inhabitants and with the help of scientists from the Insect Biology Research Institute (Irbi) in Tours. It is believed that it arrived through the transport of ornamental plants, often surrounded by clods of earth, perhaps in the fashion of olive or palm trees arriving from all over the Mediterranean. Scientists also make the link to global warming because they find environments with us that are welcoming. It is a species with a very particular behavior, very invasive, and that brings strong inconveniences.

Namely ?

The ant Tapinoma Magnum Live in super colonies. They spread particularly fast, without competition from other anthills. We can recognize them with the naked eye because they are very small and have an extremely gregarious and hyperactive behavior. They are mainly found on degraded land, cuttings. But there are also a great number of them in the gardens: they abound everywhere and if you go out, they climb on top of you. A lady confided in me that this is why her grandchildren no longer came to her house in the summer! They do not bite but they have a very invasive side. Another peculiarity, they give off a smell of rancid butter when crushed…

And they hurt too…

Yes, especially in orchards, we have seen courgettes or young tree seedlings completely attacked. In fact, these species that do not have predators create a vacuum around them: in the sectors where the Tapinoma Magnum prosperous, our classic ant is at risk of disappearing in the coming years. Thanks to the pipes, cables, they are also introduced into the houses… We had electric meters that jumped in some inhabitants! This makes daily life difficult for some of those affected. Last year, it took a considerable scale, people were completely helpless, so we had to come up with a scientific and framed approach, with a lot of education.

What can we do with these ants?

As soon as the species is identified, it should be treated immediately. Which we couldn’t do fast enough here, with now a 40-acre district in question, and an appearance of these ants in two cemeteries as well. Scientists tell us that we are not going to be able to eradicate it, so we contain it, we limit it as much as possible. We have voted financial aid for three years to carry out three treatments a year on the affected people. Regarding public spaces, we treat every 15 days from March to September with a spinosad-based product that can be used in an ecological way. The results are quite positive.

the Tapinoma Magnum » seems to be gaining ground in France, especially in the West…

Saumur acts as a laboratory for all of France and regularly the municipalities call me to ask how we do it. It is therefore clear that we are going to talk about this ant again, here but also in other places, and in particular in the Loire Valley or Loire-Atlantique, where it has been identified, for example, in Ancenis. We will see how the species evolves, there may be surprises. Near Pau, there is a village where the ant disappeared in a summer, for no reason… Let’s cross our fingers that it happens to us! There is also the possibility of another invasive species arriving and discouraging this one. Meanwhile, the drop in temperatures should offer us a period of calm, until March.

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