Buddlea problem.

[Scorpio11]

I have seven buddleas in my garden but on one of them the growing tips of each branch has either been eaten or has died back. Black ants are present on these tips.

 

[Esther Knapicius]

plant Joe Pye weed. butterflies like it better. a native plant also. no issues.

 

[Owdboggy]

Aphids. The ants will be 'minding' them. They 'milk' the aphids for honeydew (basically aphid wee).
Do not plant Joe Pye weed, it can be a terrible seed thug in Britain. Have a look at the way it is taking over the walk between Parkgate and Neston on the Wirral.

 

[Oliver Buckle]

plant Joe Pye weed. butterflies like it better. a native plant also. no issues.

Not native to Wrexham, there are issues in the UK.
Agreed, ants, probably means aphids.