Paint Thief

There is a paint thief in my house. I have left my watercolors on the top of my dresser/closet/shelving unit, and come back to it to see all the drops of paint have disappeared, only the dried watered down paint remains. First I thought it may be due to the moisture in the air, but realized my clothes would be growing mold by now if that was true. So it is either the tiny ants that wonder around the house, the moths that come in late at night, or perhaps a Tico leprechaun that has an artistic side. Either way the investigation is on.