[Obama_Is_Sabotaging_America]

Bees can kill them, with some effort. They somehow raise the Co2 levels around the wasp, thus killing it. Bees can tolerate higher Co2 levels than the wasp can.

[Resolute Conservative]

I saw some science show where they showed that and they raise the temp inside their hive when attacked.

[Ken H]

I was thinking they raised the temperature, which apparently the hornets don’t tolerate very well.