I have been tossing the spent coffee grounds, filter and all, under my cycads and have noticed scale is all but gone. If I find some, usually just a tiny few specks, I just remove that frond. It has worked so well I have started using them on a camellia that gets scale. I have about 2 dozen camellias and strangely (and fortunately) only one has been plagued. Once again the coffee grounds are doing the job. Spreading spent coffee grounds on the soil surface of container plants in the house seems to have eliminated the fungus gnat issue. I am a convert.
Edited to add - years ago I worked at a large commercial greenhouse and one day I had to call an ambulance because the owner had been spraying Orthene and next thing I knew he was unconscious. He had inhaled the spray and it almost killed him.
