[Ag-eq] Have I found a harmless deterrent that will keep the little buggers away?

[Jewel]

My cabbage and cauliflower plants have been taking a real hammering from the cabbage white 
butterfly.  I have sufficient bother getting them to grow in the first place, , and when I am 
successful, a rather too rare event, along comes the flying white menace, and I might as well have 
saved myself the trouble;  however,  I may have found an organic  deterrent:  coffee grounds!
It is only recently that I have started drinking coffee made with ground beans, and being one who 
finds  throwing anything organic out, highly offensive, I have been keeping all my used grounds and, 
having heard that adding coffee beans to compost is a very good thing, I wondered if they might have 
other uses in the garden, so, to this end and  as an experiment, I have been keeping all my used 
grounds with added water, and have been watering the cabbage plants with it.
They have made a wonderful recovery.
I have no doubt that the caulies would also, but unfortunately, I am a very moderate coffee drinker, 
so don't have enough residue for them as well.

          Jewel