Unmasking the bycatch: New records and faunistic value of Phoridae from CO₂-baited traps in Slovakia

Carbon dioxide–baited BG-Sentinel 2 traps are widely used for mosquito surveillance, but their bycatch (often dismissed as irrelevant) can reveal surprising biodiversity. In this study, we analyzed the non-target captures from 414 such traps deployed at 16 localities across Slovakia in 2024, focusing on the scuttle fly family Phoridae. Despite a modest detection rate of 6.52 %, we identified 44 phorid species, including five recorded in Slovakia for the first time: Conicera similis, Diplonevra freyi, Pseudacteon lundbecki, Megaselia insons, and M. mimodensior. These findings raise the known national phorid fauna from 254 to 259 species. Several species such as Megaselia albocingulata, M. verralli, and M. involuta were widespread and abundant, suggesting ecological generalism. Others appeared only once, highlighting the value of broad and sustained sampling. Our results underscore the untapped potential of repurposing CO₂ trap bycatch for biodiversity research – an efficient, cost-effective tool to uncover hidden insect diversity.