Changes in phenology of hoverflies in a central England garden

1. Hoverfly data, obtained from 20 species during 1991-2007 from a single garden in Peterborough, England, were analysed to test for temporal trends in timing of first and last appearance, flight-period length and maximum number. 2. During this period of climate warming, first appearance in spring has become significantly earlier for three species and flight period longer for a different set of three species. 3. Key correlates of first appearance date and flight-period length were winter temperature, which increased over the study period, and spring temperature which showed a non-significant warming trend. Wetter summers also marginally lengthened the flight period. In addition, there were significant year effects, suggestive of population responses to changing climate independent of prevailing temperature. 4. However, there was little evidence that last appearances in autumn have become later, and maximum numbers have not increased. 5. These trends match those reported from other, better-studied taxa.