Flight of a fly (image 2 of 4). View of a hover fly, Volucella sp., in flight. The fly is half way through its downward stroke with its wing in a horizontal position to produce maximum uplift. For the upstroke the wing is rotated to a vertical position. The hover fly family, Syrphidae, is one of the largest fly families, containing several thousand species. Hover fly adults live on the nectar produced by flowers. Although harmless, their orange and black stripes mean they resemble wasps and bees which have stings. This mimicry deters potential predators. See Z340/436, Z340/438 & Z340/439 for the other images in this sequence.