After pupae pupate on paper towel, I cut out the pupa and tape it to the top of a 32 ounce squat tub.  I cut a hole out of the lid and attach butterfly net material to create airflow within the squat tub.  I keep the tub dry until the last 60 days of my overwintering cycle.  During these last 60 days or so, I either mist spray water inside or I fill the tub with 1 inch of water.  I check the tub every week to either spritz it with water or make sure there is water below.