They were hungry

 I looked into the hives today to see how the bees were doing with their sugar discs.  Olea's bees had not only eaten all the sugar, they were also eating the plate.  

The white crumbly stuff is chewed up paper.  There is no more sugar.

 The bees in #1 had finished all their sugar, so I put a disc in the Vivaldi box and they immediately started eating.

#2&3 had yet finished their first serving.