If I were the scientist behind these things, I'd program them with Aasimov's ill-concieved Zeroth Law of Robotics (a robot must always act in the best interest of humanity and may break any other laws and directives to do this), lie down and wait for us to get what's coming to us. (TVTropes nerdiness: http://tvtropes.org/pmwiki/pmwiki.php/Main/ZerothLawRebellion )
Even though this is fake, RoboBees have actually been in development at Harvard for the last ten years or so. They've hit a brick wall though because they haven't been able to figure out a viable microchip and power supply that would fit into such a tiny robot.