How does chewing tobacco cure a bee sting?

No. There are some homeopathic remedies that are minimally effective but chewing tobacco isn't one of them. Once ago people used what little they had for whatever they needed. Sometimes the result was satisfactory but sometimes it simply served as a placebo. Think mom kissing a boo boo.

I disagree entirely. I've had a wasp sting and had very intense pain and it stopped immediately with wet tobacco applied directly. I've read it is because nicotine acts as a local anesthetic for the pain. So not a cure so much as a pain killer.