Semaphore fly (Poecilobothrus nobilitatus) (female)

This species is one of over 300 species of Dolichopodidae in the UK, and is notable for the white tips at the end of the wings of the male which play a vital part in the male's wooing strategy.

They congregate at puddles and ponds, where a large number of males will try to impress a female with short bursts of wing-vibrations lasting a fraction of a second, where the white tip stands out conspicuously from rest of the darker wing. He then usually hovers briefly in front of her before starting the acrobatic display flight.

Helicopter-style, he arcs over the female, at about 8cm distance and just above her, back and forth. Half-way through the arc, he flips so he finishes still facing her, and remains airborne.

This happens so quickly it's impossible to see with the naked eye.