[JaK]

Are ants killing off my broad beans? There seems to be ants all over them at the moment. The broad beans have little blue/black dots on some of the leaves that the ants seem to like, then the leaves seem to die back.  Is there anything I can do?

[Kleftiwallah]

I think by your description that the "little blue black dots" may be aphids, the curse of the gardener. 

The aphids are sucking the sap from your plants and the internal pressure of the liquid within the beans is so great that it goes right through the aphid and is excreted at the other end. 

This we call honeydew and the ants lap it up.    It has been thought that ants actually 'farm' the aphids to obtain this honeydew.  If you forcefully spray water with a touch of washing up liquid disolved in it, you will dislodge the aphids and the ants will go away.   Cheers,   Tony.

[pigeonpie]

It sounds to me like the ants are starting to farm aphids, using your broad beans as the farm!
Aphids love broad beans, ant loves aphids.  Ants will start to lay a sticky sugary substance on the plants encouraging more aphids so that they have more to eat.
The best thing to do (in my opinion) is to spray them with a mixture of soapy water and brush any aphids and ants off.  Just out of interest I use Ecover washing up liquid as it is plant based and therefore completely safe to use on edible crops.

[lancashiregardeninggal]

I watched Alys Fowler's show 'The Edible Garden' yesterday and she showed how in her garden that ants were sucking the life out of the aphids (blackfly) that attack broad beans - the ants are actually doing you a favour - I've seen this in my garden in previous years

[8doubles]

I watched Alys Fowler's show 'The Edible Garden' yesterday and she showed how in her garden that ants were sucking the life out of the aphids (blackfly) that attack broad beans - the ants are actually doing you a favour - I've seen this in my garden in previous years

Ants take the sweet excreted waste from the aphids and will actively  protect the aphid from other predatory insects.
The only favour that ants do is letting you know aphid are there.

[rusty100]

I had ants last year in the polytunnel and they didnt do any damage at all.

They are back again this year, im just going to live with them and let them get on with it.