Ants climbing on your plants can be a sign of aphid infestation.
It is unusual to see ants climbing around on plants so seeing this can be sign of aphid (either greenfly, blackfly or whitefly) infestation. Ants actually “farm” aphids because of their love of the sweet honeydew that aphids excrete after consuming plant sap. They act as protectors them from natural predators such as ladybirds and can even move their eggs to different plants.
Removal of the aphid infestation is recommended, using the many chemical sprays that can be bought in garden centres and DIY stores. Always follow the instructions on these sprays. If you wish to use organic solutions to remove aphids then the ant population must be controlled first.
Ants can also cause other problems in your garden, not to mention if they get in your home, so should be removed as soon as possible. Ants will always lead from the nest to a food supply so it should be easy to spot the nest. It can be dug up and the queen destroyed or moved to another location.
Boiling water can be poured onto the nest as effective way to kill the nest, but this is not suitable if the nest is within a lawn for example as it will kill the grass as well. Soapy water is another good way to flood the ants nest but needs to be repeated for several days.
As soon as the ants are removed then organic solutions can be used to removed the aphids. Without the ant protection natural predators will soon move in, but you can also use soapy water to wash them away as this prevents them from gripping to leaves or stems. Again this will need to be repeated daily until the infestation has been removed.