Yes they are usually a sign of aphids and ants do eat them. I think my compost is too dry if there are ants in it, so I give it a soaking.

Ants farm the aphids as they eat the aphids excretions of plant sap. They will literally pick up aphids and maneuver them into a desired place.

I find if ants are running up a plant, they are normally doing it for a reason, and that reason is normally farming aphids. So i take it as a warning and have a good look to see whats going on in their little world.

So they are a indication that other pests are about, and I can presume that they are beneficial in the garden if they are eating other insects and not harmful to other plants so no need to remove them from the compost heap/bin just let them get on with what they are doing ? Thanks for the swift reply.

I dont want them in my compost, so I water it as they hate the wet. Ants are more of a nuisance than a pest really, as they feed mostly on insects, and honeydew excreted by aphids, so if you see them on your plants you need to get rid of the aphids. Ants nests can undermine plant roots to so you need to treat them.

It's not just a matter of not wanting them in the compost bin. If they're in there it indicates that the contents are too dry - so won't rot down properly. Give the composter contents a good watering and stir them up to get it going again, and to get the ants to move out.

You could remove the aphids from the blackcurrants by squishing or hosing them off, then the ants would go back to being almost invisible in your garden again.

Hi Flodden,

Like Drc726 said, they eat the aphids honeydew excretions, but the ants do not eat the aphid's.

I would not say they are beneficial, not for me anyway... they herd the aphid's so they can make an aphid problem worse. The ants want as much out of the aphids as possible, so it is in the ants interest to place the aphids somewhere where they will thrive...which can be on a plant, we as gardeners do not want eaten.