Over recent years a range of miniature drones, or micro air vehicles (MAVs), based on the same physics used by flying insects, have been presented to the public.
The fear kicked off in 2007 when reports of bizarre flying objects hovering above anti-war protests sparked accusations that the U.S. government was accused of secretly developing robotic insect spies.
The following year, the US Air Force unveiled insect-sized spies 'as tiny as bumblebees' that could not be detected and would be able to fly into buildings to 'photograph, record, and even attack insurgents and terrorists.'
That announcement was five years ago and, since the U.S. military is usually pretty cagey about its technological capabilities, it raises the question as to what it is keeping under wraps.
Researchers have now developed bio-inspired drones with bug eyes, bat ears, bird wings, and even honeybee-like hairs to sense biological, chemical and nuclear weapons. And the U.S. isn't the only country to have poured money into spy drone miniaturisation. France has developed flapping wing bio-inspired microdrones.