What can I do about an ant infestation in my property?

Reader Question: We have a recurrent ant infestation every few months in one of the rooms of our house. What can we do? Is it worth contacting the mairie about it? 

There is no single reason responsible for ant infestations in French homes, but there are a few things you can do to minimise the risks. 

Issues that can cause infestations of insects and other pests – damp conditions, open food, cracks and holes in walls, etc – are also ideal conditions for ants to enter your home. 

This is particularly the case for sugary foods, and hot weather can also lead ants to seek shelter indoors, particularly if there is moisture or condensation. 

If you live in an urban area, or in a shared building, the issue may not even stem from your property, and the ants could be coming from a nearby property. See if you can trace where they are coming from, and talk to these owners if possible. 

For rural or detached homes however, the ants may be coming from a colony on or near your property, and it will be up to you to deal with them.

Once a colony is established in your home, it can quickly thrive, particularly if the conditions that attracted the ants are not dealt with. 

This is why keeping a home clean, and the property structurally sound, is important. If ants are inside your home despite it being kept clean, there will be a deeper reason for the issue, which can require further professional attention.

Different species, different solutions 

You should not attempt to tackle an infestation without first knowing the type of ant species in your home. 

France is home to several native and common ant species, as well as some invasive groups from abroad.

This includes Tapinoma ants, which give off a distinctive foul smell when crushed, and electric ants, now present in the Var along the Mediterranean. 

Identifying the type of ant will help you better deal with the infestation, including a long-term solution. 

Use the internet to see if you can work out the type of ant, or otherwise contact a pest control expert (who may also be able to help you get rid of the issue) to identify them.

You can find a suitable  pest control expert online by searching for ‘lutte contre fourmis professionnel’ in your location, resources such as the yellow pages (https://www.pagesjaunes.fr/activites/desinsectisation.html), or going to your local pest control shop for advice. 

Many native species can be killed using diatomaceous earth, a natural powder containing silica, which can be the first port of call.

It can be purchased in supermarkets and pest control shops for a few euros.

If this does not rid you of the ants, or they keep returning, most native species can be killed using commercial pesticides, also available in supermarkets and pest control shops.

However, you should try to limit the amount you use to minimise the potential health impacts on residents. 

For larger infestations where a colony is present inside or close to the property, pesticide may not be enough and you will need to tackle the nest itself to prevent the ants from perpetually returning.

Invasive species will require specific, stronger pesticides, or in some cases special equipment. 

For these cases, you should use a pest control company and not attempt to fight the invasion yourself.

Note that it is typically easier to kill ants inside your home during winter – they are weaker due to the cooler temperatures – but it can be harder to destroy nests and colonies, as worker ants do not return to spread the pesticide to others.

However, as the colony is weaker it can be easier to tackle it directly, if you know where it is. 

Again, you should hire a professional if you need to destroy a nest or colony rather than attempt to destroy it yourself.

Who should you contact? 

Depending on the size of the colony, however, you may not be able to successfully deal with the issue on your own.

Even if you manage to destroy a single nest, ant colonies can stretch across swathes of land, requiring a joint effort.

For returning infestations of native species, speak to neighbours to see if they have experienced a problem, and see if you can work together to destroy the colony.

If you live in a shared building, you should contact your property manager (syndic) from the first instance both to highlight the issue and see if there are others who are affected.

If the issue stems from common areas in the building (cellars, lifts, hallway, etc) then the property manager must immediately contact an exterminator, without waiting for the annual general meeting. Costs are shared on a pro-rata basis between co-owners.

Tenants can also inform their landlord of any issues. 

Landlords are required to pay for pest extermination, unless they can prove it is the tenant’s lack of upkeep that has caused the issue, in which case they can bill the tenant.

For persistent infestations, or for invasive species, you should also contact the mairie. 

They can help organise a wider response, particularly if several residents are having issues and there is a wider colony affecting the area.  

If the issue persists because of a neighbour’s actions, it could be classed as a neighbour dispute (trouble anormal de voisinage). 

You can formally ask the neighbour to deal with the issue, after which you can take further action, contacting the police or a conciliateur de justice. Read more here.