I think if you look closely, you will see the hard body parts of the workers (legs, thorax) have a burnt orange color rather than black, and the bands are a bit lighter. Maybe it's something else causing it, but when I watch the bees coming and going in my hives, I see a number with this brown/orange tint on the legs and thorax. I attributed this to some cordovan background somewhere along the line. Guess I wil find out when I get the new queens later this year.