Ants usually prefer to eat sugar and will feed on the honeydew secreted by aphids. So if this is the case then removing the food source (aphids) should help. If aphids isn't the problem then you need to get rid of the ants without using insecticide or something that's poisonous as you want to eat the lettuce and leeks. I have heard that soap, salt, cinnamon, mint, peppers and coffee grounds will work but I've never tried them. To kill the ants off quickly pour boiling water on the nest.

No aphids, Myron, and don't know where to start getting rid of the ants. Wherever I dig in the veggie patch they are there under the soil, with no real sign of nests. Your ideas sound good, although as salt kills my dandelions it may not be so good for lettuce! If I find a nest I do use boiling water though.

I still think its slugs or snails. They are obviously tea total and don't like the brand of beer you are using!

Nothing wrong with French beer, Hic!... À la vôtre ;o)

I dug down below a dying leek and found a large fat grub. At first I thought it was the dreaded vine weevel, but this has legs and a brown head. I've now identified it as a cockchafer grub. Hope it's the only one, I shall be keeping a close eye on the plants!