The same thing happened with my Echenacea plant. I uprooted it, washed away all of the old potting mix, then gave it a bath in Hydrogen Peroxide solution. The HP kills everything, bugs, mold, bacteria, fungus, etc. The plant made a complete comeback and is now finally starting to bloom.

Hopefully the parts will grow on, but I wanted to give some advice about ants in pots. Keeping the base of the pot off the ground is critical to stop this happening, so if its on a hard surface (like paving) put something underneath the pots to raise them up, doesn't have to be by much, half an inch is fine. Dust beneath with ant powder periodically, and if its a big pot with a permanent plant, using a jeycloth or similar in the bottom prior to filling with compost also helps to keep them out.

Thanks Bamboo. This pot was on the ground. I’ve never seen so many ants in my life!

Horrible when you turn the pot out isn't it ... I felt like a murderer with all the eggs, but had to leg it for an hour cos of all the soldier ants trying to bite me. They were in a large pot with a sickly looking Rhododendron (years and years ago) and they'd chewed off the roots to enlarge their nest, almost all the pot was ants' nest...

Any truth in the theory that ants hate ground cinnamon?
Or is it just that they have no objection to the smell but the fine particles get into their joints in the same way as expensive remedies like diatomaceous dust do?

There's some evidence that high strength cinnamon oil puts em off, simply because they dislike the smell, but since the right strength oil is expensive and needs to be applied frequently, unless they're invading your home and you're desperate, I wouldn't consider it a viable option. The trouble with these sorts of remedies is, they become urban myths, so you finish up with people littering cinnamon sticks or powder all over the place, which is largely ineffectual.

Thanks everyone. I panicked and actually emptied the compost AND the zillion ants and eggs at the end of the garden....I’m worried now that I’ve created ant Armageddon! Now the torrential rain has stopped I’m just going to pop to the end of the garden to see what I’ve done. Wish me luck!

Ok. Big mistake. The ants are EVERYWHERE!! We have cats - and our neighbours have cats and dogs, can anyone recommend a safe ‘eliminator of ants’ please?

Take a trip to the Home Store (We have The Home Depot here in the US - a store like that) There is a huge section devoted to pest control. You are bound to find exactly what you need. Maybe it's Terro Liquid Ant Killer, D-Con or Combat, if available in the UK. Any one of these tried & true methods will work. (Maybe you can snap up a bargain or two at the Garden Center, if they have one).

I really wouldn't worry too much - you've destroyed their nest, where they would usually hibernate as the weather gets colder, so they'll head off to other places, probably carrying the eggs if at all possible. That's why they're still hanging around, they're desperate to save the eggs.. If you are concerned, you can dust the area with ant powder, but all ant killing products are not healthy for other animals either...

This year has been one of the worse I've known for ants. Only this week I was potting something on and found it was filled with red ants. I emptied and sprayed as much as possible with ant spray but I'm going to try the things Bamboo says in the future.

...and check out the pet proof Combat Ant traps. My cat won't go near it.

Maybe we just have to live with them - we do here. This year they have been everywhere -under the paving blocks, in the big urn on the lawn, even a large nest in the compost bin. They have never done any harm (except excavating sand from between the paving blocks and the occasional small bite.) I did lose a lavender bush years ago when they built a nest right under it but have never lost anything else except my patience. They are amazing creatures though aen't they, and passionate about their eggs!
Borax powder deals with them but now you can only get borax substitute & I don't know if that works. I used it years ago when some got into the kitchen cupboard...

Like Steragram, this year we have had many more ants than usual and closer to the house than in past years. When I discovered ants in my kitchen I recycled the glass pots (1"high) which had contained crème brulee by putting some honey in the bottom then covering them with cling film. I just punched a hole in the top. The ants jumped in in their hundreds. You might try using jam jars buried in the ground with syrup or something similar in them. Use the jam jar lid with a hole punched in it. It is totally environmentally safe for pets.