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V. Vulgaris S. Silentis H. Pendulus S. Ribesii M. Florea

FIGURE 10.1 Typical flight trajectories between flowers of a wasp Vespula vulgaris and its potential mimics: Serricomyia silentis, Helophilus pendulus, Syrphus ribesii, and Myathropa florea. Flowers are approximately 10 cm apart, and the time between points is 0.04 sec.

slow, convoluted flight to mimic wasp flight even though it is capable of fast flight. The other species are more secure in their morphological mimicry and so do not attempt to behave like a wasp. There is some evidence for this hypothesis; if Sericomyia silentis is threatened, it adopts a characteristic wasplike zigzag flight pattern whereas Syrphus ribesii flies off rapidly (personal observation). These results support the hypothesis that poor visual mimics adapt their behavior to be more like their models but retain their ability for rapid escape flight. Better visual mimics may only use behavioral mimicry when they perceive danger. There is ongoing work that looks at another aspect of flight mimicry in hoverflies: the flight trajectories of bumblebees, which often have a particularly clumsy flight, and their hoverfly mimics, especially their movements in the vertical plane.

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