I was just curious if they could unplug holes if they knew syrup was on the other side. I may try one and see what the do.
I was unable to train my bees to clean the holes, good luck with yours.
FWIW, my favorite feeder is a one gallon plastic honey bucket (mann lake), the lid of which I perforate with a dozen holes with a hot paper clip. (Unfold the paper clip, hold it with a pliers and heat it with a torch til it glows red hot.......The red hot wire goes through the lid PDQ).
The bucket goes upside down over the hole in the inner cover, then, protected from robbers and the sun by an empty hive body and an appropriate hive top. I rarely feed to put on winter reserves, so, the dozen holes work well for stimulative feeding at various situations during the year. HTH