Chris Hogg wrote in message . ..
Nicotine is a powerful alkaloid insecticide and was available to
amateur gardeners fifty or so years ago. However it is also very
poisonous to humans as well as being addictive, and is now only
available to commercial growers (AIUI). Even they have to adopt
stringent safety precautions when using it.

Tobacco leaves typically contain about 5% nicotine. Someone on a
recent thread (I think it was one on red spider mite) mentioned almost
jokingly that they'd heard you could make an insecticide by soaking
old cigarette butts in water. Is there an old-established recipe for
doing this (so many ounces of tobacco per gallon, soaked overnight, or
whatever) that gives a nicotine solution of sufficient concentration
to be insecticidal but harmless to us mortals? Is there a harmless
concentration? After all, smokers happily puff their way through
umpteen cigarettes a day, and whatever long-term illness they die
from, acute nicotine poisoning isn't it.

Actually there is sime evidence that nicotine itself encourages the
growth of cancers.
--
Neil Jones- http://www.butterflyguy.com/
"At some point I had to stand up and be counted. Who speaks for the
butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn
Bog National Nature Reserve