I paint the alighting boards on my hives different colors too. Does it help? Hard to tell, but I know it doesn't hurt and it makes it easier for "me" to differentiate the hives. Instead of C1, C2 like John. Mine are blue, yellow, red, etc....
I know a fellow beekeep that cuts different shapes (circles, squares, etc) out of plastic jugs (ie. orange Tide detergent) and tacks them above the hive entrances.
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