A team of engineers from the University of Southern California in Los Angeles built a four-winged flying robot called Bee+ , which weighs just 95 grams and sports a footprint smaller than a penny.

Harvard researchers built another tiny flying robot, called RoboBee, in 2013. It weighed only 75 grams.

But RoboBee featured just two wings, which made its flight far erratic and uncontrolled. Four wings gives Bee+ a way to control pitch and its orientation in space.