1mL tea tree oil to your 100mL water will do it. Alternatively, if Thursday Plantation still sell a tea tree shampoo, you can just use that.

I had them a while ago - ewwwww, I know! Never usually get them, but now that I'm preggas, apparently I'm a bit more habitable! Anyway, all I did was wash my hair once a week with a bar of tea tree soap, and they're gone. I even had my hairdresser check before she put any of her tools near my head, and she couldn't find anything. It's amazing stuff.