If you have smoked for a long time you have already smoked thousands of spider mites...That being said I hate the little bastards but when I do catch a case of them I let my plant go all the way to harvest.. A 5 week plant will produce a weak ass buzz, I would rather let it do its thing and when you harvest cut the whole plant and hang it upside down. The spider mites do not like being upside down for some reason and they all gather at the top end of stick...

I have done this a few times and it tends to work...