Ignore them - ants and paeonies sort of go together. It used to be thought it was the ants' activities that made the flowers open, but that's been disproven. Provided you haven't seen any aphids infesting the plant, they can safely be ignored - there is now a theory that the ants are simply patrolling and shielding the plant, awaiting the flowers opening to get at the nectar before anything else does, and in fact, keeping off aphids.

Ants are attracted to and eat the sweet nectar secreted by the peony bud. Ants do not harm the plants, and the flower buds do not require ants to open. However, as the ants patrol the peony plants in quest of the nectar, they may attack any other insect and thereby protect the peony. You don't need to do anything; the ants will disappear once the flower opens.

Thank you both very much for the info. I sort of thought it was ok. Ants don't usually cause any problems, but it's reassuring to have that confirmed. Another fascinating garden collaboration!

Bathgate's answer is more accurate than mine - I only found out about this in the last few months, and had forgotten where the nectar was being produced, and didn't bother to check!

How interesting all these relationships are. No wonder things get messed up when humans try to tweak nature. Every tweak has a whole raft of consequences.

Yes, which is the worry we all have here about GM crops of course, and what the knock on effects on the environment might be. But usually, of course, ants on plants does mean an infestation of scale or aphids - paeonies are an interesting exception.

Is it not true that ants do not kill some aphids but milk them - so spraying is needed some times ?

Ants do indeed milk aphids, and protect them in order to do so. But the ants don't themselves harm plants. An infestation of aphids requires some sort of action. I find that I usually have enough birds - especially tits - who generally keep the aphid population down. The one exception is if I try to grow nasturtiums. They invariably end up covered with blackfly, so I avoid them.

I simply spray them off with the garden hose.

Triffidkiller - ants don't exactly 'milk' the aphids, but they collect the honeydew they produce - same is true with scale infestation. Ants, on most plants, are a sign that there's another problem going on - except on paeonies!

Yes I knew they collected the honeydew but it is called milking its an old term that gardeners use were I come from

Isn't it interesting that these tiny creatures exude honeydew? Presumably it contains sugar, so it suggests an excess of energy. Of course, I might be totally wrong about that. We have to park our car under a large sycamore which grows in the road outside our house, and in the summer, the car roof is covered in honeydew - usually swilled off. We went up to the NE coast and left the car in a car park. When we returned it was covered with wasps - and was given a wide berth by adjacent parkers ( and our daughter!) - and we reached a decent speed before we had seen off our visitors!

Oh my word, wasps, I wouldn' t have been keen to get in the car at all!

I wasn't too keen myself, Bamboo! They were - fortunately - only interested in the car roof!

Good job it wasn't near the end of August - they're so dopey then they sting anything nearby...

We've had a couple of wasps' nests in the last few years - mostly they are ok, but they apparently run out of sugar by late August, and begin foraging. That's when they become a nuisance. Interestingly, I was told by a bee man that wasps will often get confused about their nest. If they find a similar house ( in a row or terrace, for example) they will make their way in by mistake. A "false nest" is then established, which is visited by an increasing number of wasps. From there, they will often find their way into the house. If it's a true nest, they stay in it and only leave to go back outside. We had that experience many years ago, finding a dozen or so wasps in our bathroom every morning. I assumed it was because there was a nest in the cavity wall, but he said "No - it must have been a false nest!" Real or false, I wouldn't want to repeat the experience. OH loves wasps (!) but I have to say he became our hero, killing all he couldn't usher out of the window!

I loathe the damn things - been stung at least half a dozen times and it stings like crazy... brings involuntary tears to the eyes.

I don't like them either. They just seem a million miles away from bees. Yet they're not, really.