Why are there ants all over my nice rose bush

[MamaErmintrude]

They're congregating at all the places where the branches 'join' IYSWIM

They'll be there because of the aphids on the bush that leave sticky stuff that the ants like to eat. Kill the aphids and the ants will go.

Excellent thank you! I take it aphids are bad...?

Yep. They are doing you a favour.

No the Ants aren't doing you a favour! They farm the aphids, preventing ladybirds etc from eating them.

Some sugar water at the bottom of the bush should distract the ants and leave the aphids unguarded.

So it's best not to have ants nests in your garden ? I have lots of ants .

Ants are fine, they milk aphids, but they are part of a healthy ecosystem.