Throughout 2010, the folks at Parasite of the Day have been exploring those hardy stowaways of the animal kindgdom. Now they are counting down the 12 Parasites of Christmas. Each entry offers the opportunity to vote—interesting, cool, funny, or yuck!

Shown, that quintessentially holiday parasite—and subject of December 17th’s Parasite of the Day—mistletoe, in a vintage postcard collected by Cheryl Hicks.