Are there any less nasty methods other than the acid?
I guess that depends on your definition of nasty.
I have no problem differentiating between hard chemicals such as fluvalinate (Apistan), coumaphos (Check Mite+) which are truly nasty and I would not use, and the soft chemicals such as organic acids which are in our diet daily. Ever eat sorrel, rhubarb, buckwheat, black pepper, parsley, spinach, chard, or beets? All of these have significant concentration of oxalic acid.
A pound of spinach has 2x the amount of oxalic acid than used to treat a hive.http://www.guinealynx.info/diet_oxalic.html