out of curiosity what did the sugar water look like in the sprayer? ie was it clear, cloudy, have air bubbles,
I guess just to eliminate it as a possibility what I am getting at is yeast strains from the air getting into the sugar water and converting the sugars to alcohol. also we are presuming you are using a totally clean spray bottle, that has never ever ever been used for anything else that could after having sugar water in it for a week leach back into it that was harmful to the bees? otherwise I'd still say don't candy the bees with sugar water, but it is strange for you 'still' to be losing them after this amount of time simply because you stickied them.