[BabyStar]

Noticed yesterday that one potato plant has clusters of black aphids at the top of the stalks. Only one plant out of the whole lot. What to do? Can I just chop that bit off? Or wash them off? I hate the things, they make me itch! There are also quite a few ants crawling over the aphids, my husband seems to think the ants will eat them but I'm not so sure... 

[DD.]

The ants will not eat the aphids, quite the reverse, they farm them for their secretions - you need ladybirds for that.

You can squish them or blast them off with a hosepipe, as you suggest, before resorting to spraying.

[BabyStar]

Aphids blasted into space by the hose yesterday, along with the body snatching ants! Hopefully never to return...