The phenology of Syrphidae (Diptera): are they Batesian mimics of Hymenoptera?

Abstract

The phenology of aculeate Hymenoptera and of syrphids which are believed to mimic them has been investigated at three semi-natural ancient woodland sites in north-west England. It is concluded that the abundance and phenology of most of the hoverflies is consistent with their being Batesian mimics of particular species of bee or wasp. The main exceptions are Eristalis spp., Helophilus spp., Syrphus spp. and Episyrphus balteatus which are often much more abundant than their supposed models. These four taxa may still benefit from mimicry, but further research is needed to confirm this. With the possible exceptions of Eristalis pertinax and E. tenax, there is no strong evidence from north-west England in support of Waldbauer's hypothesis that mimics are rare when fledgling birds are abundant but may be commoner in autumn and spring. The data also indicate that mimics which closely resemble their models (specific mimics) are usually rarer than their models, whereas mimics with a less precise resemblance (non-specific mimics) are often commoner than models.