Spraying can after can with no result? You're not alone. Several recent studies confirm that some populations of German cockroaches are developing resistance to the most common insecticides — a phenomenon that makes home control much harder.

Why resistance develops

Cockroaches breed fast and in large numbers. With every poorly dosed treatment, the most resistant individuals survive and pass on their genes. As a result:

• contact sprays kill a few visible individuals but not the nest;
• some roaches now avoid sugary baits (glucose aversion);
• repeated use of the same active ingredient speeds up the selection of resistant strains.

The methods that really work

An effective treatment relies on a combined strategy rather than a single product:

1. Diagnosis of nesting areas (behind appliances, under the sink, in ducting).
2. Professional gel baits with a cascade effect that contaminates the whole nest.
3. Rotating active ingredients to prevent resistance.
4. Strict hygiene: removing sources of water and food.

A cockroach seen in daytime is often the sign of an already well-established infestation: most of the colony stays hidden.

Call a professional

Against a resistant infestation, a professional makes the difference: approved products, controlled dosing and follow-up until complete eradication. It's also essential for restaurant kitchens subject to hygiene standards. Contact ProDeratisation for a guaranteed treatment.

For prevention, quality gels and traps help keep populations in check between two interventions.