Hi Guys, There was a study conducted in Europe and published in the American Bee Journal that studied the varroa mite life cycle using a video camera and clear, plastic cells containing brood. At one point the varroa mite migrates from the posterior end of the bee to a feeding site toward the middle of the abdomen. The mite must push the pupa's legs out of the way to get there. Maybe with smaller cells, the mite makes more 'noise' and can be detected easier by the bees. Bees use this same brood cleansing behavior to handle other pests as well. Bald headed brood has been reported in association with wax moth infestation. Barry Birkey has some excellent photographs of this process at: http://www.bee-l.com/biobeefiles/barry/index.htm Although the mechanism appears to be the same, there are a number of differences that distinguish the bald headed brood due to wax moths and the same associated with varroa infestations. Others have reported a limited amount of bald headed brood without an apparent cause. This cleasing activity doesn't involve dead pupa. When they are uncapped at the purple eye stage, the pupa are glossy white and quite alive. And they remain alive unless the bees chew them out. Here are some photos of bald headed brood: http://www.bee-l.com/biobeefiles/mitechew/index.htm Click on the thumbnails for a better view. I'm sure that there are multiple ways bees combat pests. But changing the cell size has allowed all different kinds of bees to tolerate the varroa mite. Regards Dennis Who has enough trouble just speaking English :>) :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::