Through the rapid expansion worldwide of impervious areas and habitat fragmentation, urbanization has strong consequences that must be understood to efficiently manage biodiversity. We studied the effects of urbanization on flower-feeding insects by using data from a citizen science program in the Parisian region. We analysed the occurrence of insects from 46 different families on flowers of different morphologies, using landscape indices in buffer areas from a 100-m to a 4000-m radius around 1194 sampled sites. Our aims were to determine (i) how the proportion of impervious area around sampled sites affected the occurrence of flower-feeding insect families and at which landscape scales impervious area calculations best predicted these occurrences; (ii) the effect of corolla shape variables on insect family occurrences. Twenty-one families were negatively impacted by increasing proportion of impervious areas (urbanophobic) and 3 were positively impacted (urbanophilic). Urbanophobic families were most affected by the proportion of impervious areas when it was estimated within buffers of 200-m to 1400-m radii, depending on the family. Notable losses of urbanophobic families were detected at less than 50% of impervious areas, which highlights the threat to the diversity of flower-feeding insects posed by urban sprawl. Corolla shape variables were the variables most often significantly implicated in the occurrence of insect families. Urbanophobic families were negatively affected by the tubular shape of flowers, and tubular corollas were found more often in urbanized areas. These results suggest that flora management might be a key component for the conservation of insect diversity in cities.