Ants in the rock garden.

[Jupiter]

I'm noticing a lot of ant activity in the rock garden at the moment, which doesn't seem to be impacting negatively on the plants at this stage. I'm just not sure whether to let it go and keep an eye on it or act now and bait them... It's a tricky one, in a sense they should be on my side, attacking plant pests, aphids, caterpillars etc. but on the other hand I've read here that people have trouble with them damaging plant roots. Any comments?

[Steve Garvie]

I would be very wary.
Depending on the species and circumstances many ant colonies will actively farm aphids and other sapsuckers. The ants produce "sedating secretions" which subdue aphids and reduce their movement resulting in higher local concentrations. They also nip off the wings of any winged aphids and protect their herds from predatory insects. The aphid herds are "milked" for sugary secretions and harvested as a protein source.

Whilst fascinating to observe the collateral damage to your plants may prove too great.

[Jupiter]

Thanks Steve, I'm considering baiting them starting tomorrow. I've already had aphids on some of my irises.

[fermi de Sousa]

Some cures are worse than the disease
cheers
fermi

[David Nicholson]

I think when you've got them you've got for them for all time, whatever you try to do. My front garden is full of them in the Summertime.  The worst patches, where I think I might have a nest and where there are no plants to damage I treat with boiling water. The rest I spray liberally but I'm never clear of them.

[Maggi Young]

Some cures are worse than the disease
cheers
fermi

 I love Errol - I won't hear a word against him!

[Richard Green]

I had ants in a polystyrene fish box trough this past summer.  They climbed up the concrete block the trough was sitting on, and chewed past the plastic mesh I had left covering the inside of the drainage holes to set up home inside.

The ants built large mounds of soil over the cushion plants whilst I was away for a fortnight on holiday.  I see they are starting to do this to yours.  Then birds began tearing up the plants to get at the ants, and scattering pieces around.

Ant Killer powder had no effect, so at that point I removed the plants, tipped out the whole trough onto a plastic sheet and left the birds to feast for a couple of days.  I repotted the trough and have had no trouble since, and suggest you do the same.  At least I have plenty of Saxifrage cuttings coming on nicely now from replanting the bits scattered around!

[Neil]

Use Ant Stop, https://www.lovethegarden.com/products/pests-disease/home-defence-ant-stop-granules , they also make it as bait station and a spray, but I found the granules best either scatter them around the ground and wait for rain, or mix them into a watering can and water the ground.

[partisangardener]

I would be very wary.
Depending on the species and circumstances many ant colonies will actively farm aphids and other sapsuckers. The ants produce "sedating secretions" which subdue aphids and reduce their movement resulting in higher local concentrations. They also nip off the wings of any winged aphids and protect their herds from predatory insects. The aphid herds are "milked" for sugary secretions and harvested as a protein source.

Whilst fascinating to observe the collateral damage to your plants may prove too great.

I would like some sources of the mentioned facts. Like seducing or nipping of wings of aphids.
The sugar will be used by ants, but if not, sprinkled all over, resulting in a lot of black mold everywhere. The sap contains too much sugar for the aphids and to little protein so the excess has to get out.

[Jupiter]

Well the little Gentiana pictured above is now D.E.A.D. You were right, wise forumists. Although I can't be sure that the ants were directly responsible it was a healthy little plant before they turned up. I will be more careful in future and purchase myself some poisonous prescription (for the ants not for me).

[Cfred72]

All ants are not the breeding of aphids. Black mold in question is called "sooty mold". Last year, I had an ant colony that had invaded a pot Pleiones. There they stood larvae, probably made it warmer in the pot. The Pleiones did not suffer at all ...
It depends on the species of ant ... And god know that there are in the world ...

[Steve Garvie]

I would like some sources of the mentioned facts. Like seducing or nipping of wings of aphids.
The sugar will be used by ants, but if not, sprinkled all over, resulting in a lot of black mold everywhere. The sap contains too much sugar for the aphids and to little protein so the excess has to get out.

A quick google search should provide some links to suitable research documenting these behaviours but here is a link to a newspaper article which brings some of it together. There are risks using any newspaper as a source of reliable verified scientific research but the underlying work reported would seem to be valid: http://www.telegraph.co.uk/news/science/science-news/3309936/Ants-subdue-their-aphid-prey-with-drugs.html

[partisangardener]

Anything said about "ants" in a newspaper  is without mentioning the species as good as a scientific finding like mammals produce radioactive dumps.
Some aphid species are products of a very long co evolution so it is no wonder that some feel more safe with their partner species.
Without their herdswoman they would be much less plentiful or even non existent.
Maybe some ant species even select for good health and mostly the ones with parasites or a disease get killed.

In our climate is a species lasius fuliginosus which uses a chemical weapon against other ants.
Some hundred to a few thousand workers skipped on a place infested with other ants will bring the locals to abandon their burrow. These shining black ants live in the trunk of alive trees and don't build in the open ground.
Collect them with a soft brush from their populated streets on the tree trunks in a glass.

Works excellent with Formica and Lasius species