Asian predatory wasp (Banded Polistes - Sri Lanka) dining on watermelon.
Apparently these Vespa Bicolor Polistes sagittarius like watermelon and like to aim for the head when stinging ...
Polistes sagittarius species is recorded from much of mainland China, Hong Kong, Malaysia, Singapore and elsewhere in Asia. They like to build nests in beautiful ornamental plants.
I have never been stung by this species on my hands or arms, it has always been right on the head! (http://www.vespa-bicolor.net/main/vespid/polistes-sagittarius.htm)