Yikes!

I find this scary. The military could have a field day with this:

Scientists at the University of the West of England (UWE) have designed a robot that does not require batteries or electricity to power itself.

Instead, it generates energy by catching and eating houseflies. Dr Chris Melhuish and his Bristol-based team hope the robot, called EcoBot II, will one day be sent into zones too dangerous for humans, potentially proving invaluable in military, security and industrial areas.

It reminds me of the Michael Crichton book, "Prey".

I can see the desire for this technology, but this can easily get out of hand.