Last year I followed up on some University of Hawaii research by
sprinkling fresh coffee grounds on my soil when the slugs got bad.

Overnight, the slugs died.

The earthworms and everything else seemed to carry on as before. Not only
were the results organically correct, they were dramatic.

I would like to encourage others to try a heavy sprinkling of fresh
(un-brewed) grounds to deal with slugs. I have a 300 sq ft garden and only
used about 2# of coffee (from a 5# can of "the cheap stuff"), so the
expense is not unbearable.

Apparently their nervous systems can not deal with that much caffeine.

Bill