Heatwave sends ants into homes: why they are appearing and what to do

As France experiences its third heatwave of the year, some homeowners are reporting unusually persistent ant problems. 

This is the case for Mary Burnett, a Connexion reader who has spent several weeks trying to deal with an unexpected invasion. 

“We have been here for five years and we have had minor incidents before,” she told The Connexion. “Usually, there is one day in the year when the ants seem to turn into flying ants. They fly around the house and then it stops.” 

However, this year the problem did not stop. 

“It has been going on for more than three weeks,” Ms Burnett said. “It is much better now than it was at the beginning, but they are still appearing in different rooms.” 

“I had to move out of my bedroom for about five nights because there were so many flying ants,” she said.

At the height of the invasion, she estimated there were hundreds of ants in the house at one time. She and her husband also noticed unusual piles of dry debris near the walls after returning from being away.

“We came home after a weekend away and found a pile of material near the skirting board,” Ms Burnett recalled. “It was quite shocking. We later understood that ants remove waste from their colony.”

The couple tried ant powder and other methods, but the ants kept returning.

“We follow the trails outside and try to find where they are getting in,” Ms Burnett said. “But every time we block one entrance, they seem to find another.”

Does the heatwave explain the increase? 

According to insect specialist Antonin Grimault-Frémy from the Fédération Départementale des Groupements de Défense contre les Organismes Nuisibles de Maine-et-Loire, which coordinates collective efforts to control regulated and unregulated species in the region, warmer weather can encourage ant activity, although heat alone does not create an infestation.

“Heat activates colonies,” he told The Connexion. “If there is also moisture in the air or the soil, conditions can become favourable for ants.”

Many common garden and household ants are native species and can usually be managed relatively easily. However, some invasive species have become established in parts of France.

These ants are often introduced accidentally through human activity, particularly through the transport of plants.

“People buy Mediterranean or tropical plants, and ants can sometimes be inside the pots,” said Mr Grimault-Frémy. “They are transported with the plants and, if conditions suit them, they can establish new colonies.”

How to deal with them 

The most important thing for Mr Grimault-Frémy is that homeowners identify what type of ants they are dealing with.

“There are many different species of ants,” he said. “They do not all need the same treatment.”

In western France, some invasive ants from the Tapinoma group have become a concern. These ants can be recognised by a distinctive smell when crushed.

“A simple first check is to crush two or three ants and smell your fingers,” he explained. “If there is a strong smell, it may indicate Tapinoma.”

Mr Grimault-Frémy also warned against automatically using large quantities of insecticide powder without knowing what type of ant is present. 

Some people increase the amount they use because they want faster results, but this does not necessarily make the treatment more effective and can expose themselves  unnecessarily to insecticide. 

For ordinary household ants, the solution is often much simpler. “Common ants are usually much easier to manage because they are part of our local ecosystems,” he said. 

Mr Grimault-Frémy recommends diatomaceous earth, a natural powder made from silica, which can be effective against many non-invasive species. 

However, invasive ants require a different approach. Because colonies can spread beyond a single property, treating one home alone may not solve the problem.

“If the colony is in the ground, treating one house will not necessarily solve the problem,” he explained. “The action needs to be collective, involving neighbours or sometimes the local authorities.”

Homeowners who suspect they have invasive ants should therefore contact their mairie, in case a coordinated response is needed.

Has anyone found any other solution that works? Send your ideas at feedback@connexionfrance.com