According to Dr Sam Fabian, an entomologist at Imperial College London, moths and many other insects that fly at night evolved to tilt their back to wherever is brightest. For hundreds of millions of years, this was the sky rather than the ground. The trick told insects which way was up and ensured they flew level.

But then came artificial lighting. With fresh sources of illumination to contend, moths found themselves tilting their backs to street lamps. This sent them into endless loops around the lamps, the insects trapped by their evolutionary instincts.