CAMBRIDGE, Massachusetts (Reuters) - RoboBees have been upgraded. The tiny insect robots are now capable of perching like a bat to save energy.

A Harvard team use electrostatic adhesion, the same science that causes a balloon to stick to a wall, to give their microbots a rest during flight.

The robot is fitted with an electrode patch and a foam mount that absorbs shock to perch on surfaces.

When the patch is supplied with a charge, it can stick to almost any surface, from glass to wood or a leaf. To detach, the power supply is simply switched off.

The new perching components weigh 13.4 mg, bringing the total weight of the robot to about 100mg - similar to the weight of its biological namesake.

It requires 1000 times less power to perch than it does to hover - which dramatically extends the RoboBee's operational life.

The upgrade brings the ultimate goal of swarms of tiny drones for use in military surveillance or search and rescue operations one step closer to reality.