Hey!
I've seen some of my New World Carniolans doing this!
On regular Plastic and wax foundation!
 I thought the bees were showing Hygenic characteristics, and were cleaning out Foulbrood or the like, so I pulled the supers and started treating with terramycin to give them a hand.
How does one tell if the brood are being cleaned out because of Mites, or because of some other brood disease?   One very weak hive definately had European Foulbrood- classic symptoms,  but now I begin to have doubts about the others- maybe it was cleaning out mites.
Ellen in Michigan
  Dee Lusby <[log in to unmask]> wrote: Mr Barry Birkey has posted a site for all 49ers now to post
pictures of their bees chewing out varroa mites in the
purple-eye stage ....

http://www.beesource.com/mitechew/index.htm