Flying insects as indicators of indoor environmental contamination in a hospital surgical block: seasonal patterns and monitoring performance

Flying insects can act as mechanical carriers of microorganisms in healthcare environments, particularly in restricted areas where strict environmental control is required. We investigated the abundance, taxonomic composition, and trap-color performance of flying insects inside the surgical block of a tertiary public hospital in Uberaba, Minas Gerais, Brazil. Adhesive traps of three colors (yellow, green, and blue) were installed at three locations within the block during two dry-season months (May and September 2019) and one rainy-season month (January 2020), totaling 27 traps. A total of 1,015 individuals representing seven insect orders and one arachnid group were recorded. Abundance increased markedly during the rainy season, with Psocoptera and Diptera dominating the assemblage, groups previously reported as mechanical carriers of microorganisms in healthcare settings. Yellow and green traps consistently captured more insects than blue traps, indicating higher overall capture yield for indoor monitoring. Our findings reveal persistent insect ingress into a highly restricted hospital environment and demonstrate pronounced seasonal variation in insect ingress pressure. We highlight the usefulness of color-coded adhesive traps as low-cost tools for environmental surveillance and recommend incorporating insect monitoring into routine assessments of indoor environmental quality in surgical blocks.