Morphological, colour and behavioural mimicry of cuckoo bees by the hoverfly Eumerus tricolor (Fabricius) (Diptera: Syrphidae)

Abstract

The hoverfly Eumerus tricolor is morphologically very similar to the females of cuckoo bees of the genus Sphecodes Latreille. This hoverfly was observed in two localities in central (Certoryje NNR, Czech Republic) and southern (Kladhas, Greece) Europe together with females of these cuckoo bees at nest sites of the bee hosts (Lasioglossum Curtis) of the cuckoo bees. Females of E. tricolor were sitting on the ground, slowly flying low over the ground and walking on the nesting site. This can be interpreted as Batesian mimicry of Sphecodes. This Eumerus species is the only European hoverfly of this genus with a very similar colour pattern to Sphecodes, and it also prefers the warm and sunny slopes and/or rocky steppes where Sphecodes are abundant. Within red-and-black hoverflies, E. tricolor is the only species showing this behaviour. It thus uses not only morphological but also behavioural mimicry.