Caladium Pest Problem... Eradicated!

It appears that my strategy for eliminating that unidentified life-sucking pest has succeeded!  Well, for the most part.  You may recall, my last ditch effort was to divide up the main tubular into individual chunks, giving each chunk a thorough cleanse in the sink and fresh new soil and container.  I ended up with 7 separate containers of itty bitty caladium parts.  Of those 7, 3 have begun to flourish and 4 have withered away.  I must not have been as thorough with the cleanse on those 4 because once again, almost over night, the pests returned and began to cover the entire stem and underside of the leaf.  If I had acted quickly, I probably could have repeated the cleaning and repotting strategy and saved those plants.  But I couldn't designate enough time in the middle of the week to execute and so they have perished.