Ants and my Peony?

I have a 25 year old Peony in my garden, which last year gave me many beautiful flowers. This year I've noticed that the buds are swarming with ants and they have hollowed most of them out while still very small. So I won't be getting any flowers at all this year. Do you have any idea what the ants could want with my Peony buds? This isn't the first time it has happened, it occurs once every few years.
I have attached a picture of one of last year's flowers.

 

I've seen ants harvesting honeydew off aphids on paeonies, but not any chomping away at the paeony itself. Are there aphids on the (remnants of the) buds?

 

Odd but I seem to remember that the peony buds secrete a sticky liquid - and it may be that that is what they are after. Sad that they have destroyed the buds.

 

Now, if you'd said you hadn't seen ants on your paeony then I would have been surprised.

I'm sure it will be the aphids like Jazid said.