Marmalade Fly (Episyrphus balteatus)
Copyright © 2007 John Powell.
All Rights Reserved.
The hoverflies of the family Syrphidae are among the most striking of the Diptera (true flies) because of their generally bright colours and hovering ability. They are abundant on flowers for much of the year, feeding on both pollen and nectar. The insects vary a great deal in size and shape, but are easily recognised by the venation. There is a 'false margin' to the rear of the wing, formed by the outer margin of the discal cell and vein 4, which bends forward and runs parallel to the wing margin and closes the sub-apical cell in the process. The true wing margin is often difficult to see. There is also a 'false vein' running between veins 3 and 4. It is really only a thickening of the wing membrane and is not connected to any true vein, but is usually quite conspicuous. Mimicry is well illustrated by the hoverflies, the main models being various species of bees and wasps. The Drone Fly (Eristalis tenax) is a good honey bee mimic, while Volucella bombylans exists in several forms and mimics several bumble bee species. There are about 250 British hoverfly species in the UK.