[Wanderlei]

Maybe they are showing a sort of hygienic trait of uncapping cells infected with varroa. That's my only guess. That would be pretty cool.

 

[Bob J]

Could be new bees emerging, particularly if they are in a group (ie eggs laid at the same time).....

 

[ericweller]

Do a toothpick test on the larvae of the chewed cells to verify that there isn't foulbrood. I learned in my certification class that half chewed cappings are one of the signs of foulbrood.

 

[AstroBee]

Pictures would be helpful.

 

[garyprunty]

sounds hygienic to me

http://beeinformed.org/2013/04/bald-brood/