Peonies and Ants
If you have peonies, you'll have ants. You can declare war on all the ants in your garden, but somehow ants will still find your flower buds.
Are the ants necessary?
You may have heard that without ants, the peony blooms won't open. Peony buds are sticky, and the theory goes that if the ants don't clean the stickiness off, the flower will remain stuck closed. This is a charming thought about symbiosis, but it isn't true. Peonies will bloom just fine in the absence of any ants at all. So what's going on?
Plants, unable to run and climb trees or fly away to evade their enemies, have evolved myriads of genius ways to thwart them while standing still. A peony's way is to produce a little sugary nectar to attract omnivorous, territorial, ever-hungry ants. The ants don't eat the peony bud, just the nectar on its outside...and any other bug that comes to edge in on their snack bar. So both parties get what they want. The ant gets that delicious sugar, and the peony gets its most vulnerable part, its chance at reproduction, fiercely protected. Still symbiosis, but a little more complex than you may have thought. Interestingly, I've noticed some varieties attract ladybugs instead of ants.
What should you do about the ants?
In my peony fields, ants are a fact of life. I've become adept at avoiding them, and mostly we don't bother each other. When I need to work with a peony bud that's covered with ants, a good smack sends them flying. Then I can do whatever I need to before they come scrambling back. Ant mounds in the grass paths never last long, since the ants object to having their hard work scattered by the mower.
Ants are hard at work in my fields, defending them from lot of other less desirable bugs. And when peony season comes, they climb right up on the buds and defend those too. Best to make friends with the security guards, in my opinion.