[ When they put the new one down they said copper would keep roots from growing back in the drain field.
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This really does work. DH was a nurseryman and put copper mesh in the bottom of pot plants to keep them from growing into the ground. And thin copper sheets put on pot tops will keep off slugs.
I also use the water in a zip loc on the back porch, it does seem to work. And instead of a fly swatter in windows I use a dust buster to suck them up instead of ugly smashed flies.