Are Nilaparvata nymphs winged?
The family-level identification I had given I now see was unnecessary; the Wikipedia site for an economically important member of the genus (there called the Brown planthopper) is here: https://en.wikipedia.org/wiki/Brown_planthopper.  The species covered there has long- and short-winged forms; other members of the genus are probably similar.  All of the individuals in the photograph above are adult.  A late-instar nymph will have wing pads (not yet wings) which are fused to the thoracic segment to which they're attached (a life-cycle diagram with drawings of two nymphal instars -- there are probably more -- is found here: http://www.cpsskerala.in/OPC/pages/ricePestbrownplant.jsp [the eighth slide]). 
 So nymphs and short-winged adults won't be flying out of danger -- they'll be hopping away.