American scientists have found that cockroach sprays don't work

In particular, products based on pyrethroids, one of the most popular groups of insecticides, almost fail to cope with the task.

A team of scientists from the University of Kentucky and Auburn University (USA) published a corresponding study in the Journal of Economic Entomology.

These conclusions were drawn after laboratory tests in which the researchers tested the effect of such preparations on red cockroaches (Blattella germanica), the most common cockroach species in homes.

The sprays are usually sprayed in areas where the cockroaches emerge so that the poison works on them when they come into contact with treated surfaces. However, experiments found that the sprays killed less than 20 per cent of cockroaches, even if the insects were in the treatment area for 30 minutes. In some cases, it took eight hours to five days for the cockroaches to die, even with prolonged contact with the insecticide.

It turned out that these products only work when applied directly to cockroaches, making it difficult to use them effectively in the home, as it is impossible to find and treat all cockroaches. Frequent use of these products has also resulted in many cockroaches developing resistance to the pyrethroids.

The researchers also found that the effectiveness of the sprays depended on the surface to which they were applied. For example, the drugs worked significantly worse on drywall than on ceramic tiles or stainless steel.

According to one of the study's authors, Jonalyn Gordon, gel or liquid baits with a slow-acting poison may be more effective in controlling cockroaches. He also recommends that for serious infestations, professional extermination services that use comprehensive pest control methods should be contacted.