Genus Polistes

How do I explain this incident, this wasp entered my house by itself, I didn't touch it, didn't hurt it but this wasp managed to sting my youngest brother's arm, of course it was an incident that I shouldn't let happen especially since this wasp was very dangerous. So the story is like this, last night when my youngest brother had just come out of the bathroom suddenly he screamed because suddenly he felt something biting his hand, it felt very painful and unbearable, my mother and I immediately ran towards him and immediately realized that he had been stung by a wasp, the wasp was still not too far from my brother, he didn't let it go and immediately took the wasp to throw it away.

Judging from the condition of its body, this wasp looks very weak and I don't know whether it bit or stung my little brother's arm, my mother forbade me from killing this wasp, but because of my annoyance with it I immediately threw it out of the house. I have to immediately check and repair the condition of the window ventilation in my house, because lately there have been a lot of flying insects entering my house through the window ventilation path.