> why this happens?


>The yellowjacket life cycle begins with a fertile queen, who builds a nest and uses stored sperm to create worker bees. These worker bees continue building the colony, and die off at the end of summer. The life cycle continues with newly-created queens hibernating through the winter to start the life cycle again the following spring.

Natalia

They could be even quite aggressive in this period of time. They have likely lost their sense of life, and have nothing to lose, they mostly want sugars so if there are many of them around you, just give them a glass of very sweet water somewhere further away from you.