You can use car axle grease,

but if you put semoliena (hope ive spelt that right) the pudding mix, we're the ants can get at it, they'll take this back to the nest, the queen ant eats it and it expands in her stomech and she dies, the rest of the ants move on and you'll have no more ant problems.

Im serious, i know it may sound strange but it works.

Taldridge, ants on your tree means its infested with aphids or possibly scale insect. The ants do not harm your tree in any way, but they like the honeydew produced by aphids and scale insects, and so 'farm' them. They presence of ants in the tree is actually a useful indicator that treatment for infestation needs to be carried out - check the backs of leaves and new shoots to see what you can find, and the trunk and branches for signs of scale infestation. Get rid of that, and the ants will disappear...