It’s rare to be blue when you’re in the natural world.
If you think of parasites, there are probably two words that won’t come to mind. One is romance; the other is Christmas. If someone told you that he had fleas or a tapeworm, your first reaction probably wouldn’t be to kiss him or to put on the Christmas tunes. But if he brought you a parasite that grows on apple trees, the humble mistletoe, then you probably would.