The University of California has made a breakthrough in its programme to develop a robot fly weighing less than a paper clip which can leave the ground and hover in mid-air.

A university spokesman said that scientists have now constructed a wing mechanism that can flap and rotate at 150 times a second.

The robots could be used as robo Terminators to seek and destroy insect pests in a field of corn. A commercial version could be on the market within 10 years.

Recent discoveries about the way flies use their wings have helped the project considerably.

A real fly has a 'delayed stall' which enables the beating wings to have a high angle of attack and high lift at the same time.

'Wing rotation' at the bottom and top of the stroke gives the insect more lift, and 'wake capture' provides even more lift by swishing back through air it set in motion on the previous stroke.

The scientists' version of the wing is made from polyester and a stainless steel strut that flaps and rotates. The wing membrane is constructed from solar cells that also power the movement.