Simple Summary Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) is an insect pest commonly found in poultry houses. High air temperature that accompanies chicken rearing, high relative air humidity and deposited chicken excreta are the factors that create favorable conditions for the development of A. diaperinus on poultry farms throughout the year. A. diaperinus is a vector for pathogenic bacteria (including Salmonella spp., Campylobacter spp., Staphylococcus spp., Escherichia coli ), fungi ( Aspergillus spp., Candida spp.), protozoa ( Eimeria spp.), poultry parasites and viruses (causing Marek’s disease, Gumboro disease, Newcastle disease, avian influenza, and leukemia in poultry). At the same time, the insect’s resistance to commonly used insecticides is observed. Therefore, it is crucial to find an effective solution to eliminate the insect. In view of the above, an attempt to reduce the population of A. diaperinus on poultry houses is the justification for this research. In the research we used biocidal paint containing permethrin and a mixture of ultramarine and violet 23 to control the number of A. diaperinus (larvae and adults) in laboratories and poultry houses. Abstract Reducing Alphitobius diaperinus in poultry production is a difficult task. However, attempts should be made to control the insect pest, as it poses a serious threat to the life and health of the chickens, as well as the workers on a farm. Our research was conducted in two stages to assess the effectiveness of the biocidal paint against A. diaperinus , containing active substances such as permethrin and a mixture of ultramarine and violet 23. In the first stage, under laboratory conditions, after 22 days, 100% mortality of A. diaperinus larvae and adults was achieved. This allowed us to assume that the biocidal paint may also be effective in poultry houses. In the poultry house where biocidal paint was applied, the number of insects decreased continuously alongside the sampling dates. In both research stages, the biocidal paint proved more effective against A. diaperinus than traditional limewash, and also the time to effective interaction of the paint was noted. Additionally, it was observed that the larvae were more susceptible to the active substances than adults. The research was practical, however, further analyses are necessary to fully control A. diaperinus , especially in poultry houses.