Has anyone ever brewed a tea from chewing tobacco or cigs and used it as an insecticide? My sister in law does this to kill fungus gnats in her african violets. I was thinking it might be just the thing to take care of some aphids. When I use soap or oils they die...then more just come right back. Maybe nicotine would work better with a little residual. OR maybe they would get addicted and I'd never get rid of them!
Tobacco "teas" are an old fashioned remedy. However, they are not considered to be acceptible organic pesticides. They are very, very toxic broad-spectrum pesticides. You should also know that using such a concoction on tomatoes would be a good way to vector tobacco mosaic virus.
I wouldn't use tobacco tea on anything. I try to never use broad-spectrum pesticides, even organic ones, unless absolutely necessary because its bad for the necessary good bugs. Even in the very few cases where I would consider a broad-spectrum pesticide, I wouldn't use tobacco tea. Seriously, the stuff is muy toxic.
In any event, aphids really don't call for the big guns. Blast them with water repeatedly to knock 'em off the plants. That and a little patience waiting for the lady bugs to arrive should take care of the problem. If its so severe that you think something else is warranted, then a soap spray should take care of them.
I used this years ago when I first started gardening. You were to take cigarette butts, snap off the filters, and soak them in water with a little dish soap added. It did work great to kill spider mites, but at the time I didn't know just simply spraying the plant three days in a row with water would work to kill spider mites just as well, and that as other posters have said, this is a real toxic brew. Nicotine is easily absorbed through your skin, and if you are like me, it is pretty difficult to spray plants without getting some of it on you one way or the other. A good thing to kill fungus gnats and not toxic at all is tepid chamomile tea. It is also just a good antifungal for plants.