I know I am going to sound like Chicken Little, but it is incredibly reckless to encourage this kind of behaviour. Seriously, this stuff (nicotine) can
KILL you!!! I know the chance is extremely small, but can you imagine someone dying because they spilled a bucket of nicotine laden water on themselves!!! The EPA states that 40-60mg (0.04-0.06g) can have a 50% chance of
KILLING someone!! Seriously, a few holes in your hop leaves are not worth even a 0.001% chance of dying!
When you smoke a cigarette, only a small percentage (~12%) of the nicotine gets into your system, so 40-60mg would mean several dozen at one time. On the other hand, when you boil yourself up some toxic nicotine soup, who knows how much is in the water? I know I would not want to even guess how much was extracted!
NOTE: Due to toxicity issues, and farmers realizing the don't want to die, the EPA has removed all registration of nicotine as an insecticide, and it will be illegal to apply in any form after next year. It has been illegal to apply to food crops since the 1990's.
http://www.epa.gov/oppsrrd1/REDs/nicotine_red.pdf
PS: +1 to it being japanese beetles