Long‐distance pollen transport mediated by migratory hoverflies

Long‐distance animal migrations shape ecosystems by redistributing nutrients, connecting populations, and mediating ecological interactions. However, the ecological contributions of many abundant insect migrants remain poorly quantified. Hoverflies are among the most numerous migratory insects and highly efficient pollinators, suggesting that their seasonal movements could facilitate long‐distance pollen transport. Despite this, the amount of pollen transfer during migration has not been comprehensively quantified. Here, we analysed pollen loads carried by the three most common autumn‐migrating hoverfly species and combined this data with revised estimates of active migratory bioflows from four sites to estimate pollen transport across western Europe. Individual hoverflies carried high pollen loads, with the largest species averaging over 500 grains per individual. Extrapolation across migratory bioflows indicates that movements between the British Isles and continental Europe alone transfer more than 300 billion pollen grains each autumn, with total annual transfer by these migratory hoverflies likely exceeding trillions of grains. These findings identify migratory hoverflies as previously underestimated agents of long‐distance pollen dispersal, with important implications for plant population connectivity and ecosystem functioning at continental scales.