According to data from the French sanitary agency ANSES, more than one in ten households in France has been affected by bedbugs between 2017 and 2022, and there is no indication that this trend is reversing. For a long time, it was believed that a simple insecticide bomb purchased at a supermarket was enough to solve the problem. Since 2020, however, thousands of households tell a different story: that of a battle already lost against an insect that has become almost indestructible. Bedbugs have developed a genetic resistance (kdr) to pyrethroid insecticides, making the fumigation bombs largely ineffective. These fumigants often worsen the situation by pushing surviving bedbugs to flee and disperse into other rooms or dwellings. Thermal treatment (more than 55°C), dry steam, and detection dogs are now the most effective methods, complemented by financial assistance from the CAF and the ANAH. This resistance was built long before the lockdown. The return of bedbugs is not a recent phenomenon. It has actually been developing since the 1990s, driven by the explosion of international travel and the multiplication of short-term accommodations. For decades, pyrethroid insecticides, synthetic molecules imitating natural pyrethrins, have formed the basis of all public treatments. The problem is that these same substances have ultimately selected populations of insects capable of surviving them. This mechanism has a name: kdr resistance, for knock-down resistance. A genetic mutation modifies the sodium channels of the bedbug's nerve cells, the same ones that pyrethroids target to paralyze the insect. As a result, the product is no longer effective, or only partially so. Several industry observers note that in Paris, local strains may have particularly evolved in this direction, making some protocols significantly less effective than they were fifteen years ago. And contrary to a persistent misconception, this resistance affects all homes, regardless of social distinction: the cleanliness of an interior does not protect against infestation at all. The insecticide bomb, an unintentional infestation accelerator. The fumigant, this small canister that one triggers before leaving the room for a few hours, remains the most common reflex in the face of a suspected infestation. However, it is precisely this action that often worsens the situation. The product diffuses into the ambient air, but the bedbugs, sensing the chemical threat, do not die immediately: they flee. They take refuge in the gaps of baseboards, behind electrical outlets, under carpets, or worse, migrate to neighboring rooms and sometimes adjacent apartments. A localized infestation in a bedroom can thus, in a single night of failed treatment, transform into a generalized infestation across several rooms, or even several apartments in a building. The survivors, now dispersed and hidden more deeply, become significantly harder to locate for a professional called in for assistance later. It is precisely this scenario that explains why so many households, convinced they have solved the problem after buying a bomb from a store, see the bites reappear a few weeks later, sometimes in a room they thought had been spared. Five eggs per day: the reproduction machine that outsmarts all calculations. Here is the figure that summarizes the scale of the challenge: a female bedbug can lay up to five eggs per day. Over a month, this represents potentially more than a hundred new individuals from a single fertilized female. Add to this a rapid development cycle, from egg to reproducing adult in just a few weeks under favorable conditions, and you get a population dynamic almost impossible to catch up with using partial treatment. This is the trap of incomplete solutions. A treatment that eliminates 80% of the visible individuals may seem like a success at the time. But if a few fertilized females survive, hidden in a crack or a mattress fold, the colony can regain its original size in barely a month or two. This ability to regenerate largely explains why the phenomenon has stabilized at a high level rather than receding, despite an undeniable collective awareness since the media panic in September 2023, when videos of bedbugs filmed in the Paris metro had gone viral on social networks and pushed nearly 40% of the French to declare knowing someone recently affected. Heat, steam, canine detection: what works effectively in 2026. Faced with this finding, the classical chemical approach has gradually given way to methods that bypass the biological resistance of the insects. Thermal treatment is the most effective example: by heating an entire room to a temperature above 55 degrees for several hours, one kills the bedbugs at all stages, including eggs, without any genetic mutation being able to oppose it. Dry steam, applied directly to refuge areas such as mattress seams or baseboards, complements this device effectively by targeting the inaccessible corners that ambient heat cannot reach. Another indispensable tool: detection dogs, specifically trained to detect the odor of bedbugs and their eggs with a precision that human eyes cannot match. This approach allows the identification of an infestation at an early stage, before it generalizes, and directs the treatment to the areas actually affected rather than treating an entire dwelling blindly. Faced with the scale of the phenomenon, an interministerial plan was deployed as early as March 2022 to intensify awareness, and assistance now exists to reduce the cost, up to 600 euros through the CAF for modest households, and coverage that can reach up to 50% of the costs, capped at 10,000 euros, through the ANAH for property owners. Two years after the Paris Olympics, which had accelerated the mobilization of public authorities and the hospitality sector out of fear of a negative international image, professionals in the sector speak of a situation that is gradually stabilizing, without necessarily retreating. What has changed, however, is the way the problem is approached: one no longer seeks to kill a visible bedbug, but to understand why it is resistant, and to adapt the response accordingly. The next time a suspicious bite appears upon waking, it is better to think of early detection and targeted heat rather than rushing to the insecticide aisle at the local supermarket.