Bombylius major (16)
|Visitor in the backyard: The Great Gonso|
You will remember, back in the good old days there was the cherished Muppet show on TV. The Great Gonso was a jerk, his nose got pinched in every door. Our 11 mm long Gonso (Diptera; Bombyliidae; Bombylius major; Bee fly; Grosser Hummelschweber) may look similar but is an accomplished acrobat. It is visiting the 8 mm wide Veronica persica flower by precision hovering, not even touching.
"Insects cannot fly, according to conventional laws of aerodynamics"(C.P. Ellington, 1996). Let me tell you what garbled thoughts came up when observing this hovering Gonso. You hardly see a trace of the wings, they beat so fast. The hum of the flight reaches about a lower b, so the wingbeat frequency is assumed to be around 250 Hz. A muscle contracting 250 times a second? When my hand trembles, the frequency reaches maybe 8 or 10 Hz, faster would result in a cramp. The wing moves hummingbird fashion forth and backward horizontally, the stiff leading edge always up front: lift is created in the forward- and the backward stroke. See picture of the wings.
There must be a flight stabilisator: its the long hind legs stretched out sideways that serve as balancers. Notice also that the eyes look both forward, allowing overlapping pictures, a precondition for stereo view. These eyes produce a hundred pictures a second (man has a frequency of 20- 24/sec), allowing the animal to apply corrections and hover precisely.
Of course Ellington knows what he is talking about. He and his many predecessors found for instance that for small insects the air is viscous like water is for man. Consequently, Psychodid flies have adopted a paddling technique for flight (see picture) !
The picture was treated in PS: patches, stamps, crop, contrast, sharpen, resize.