how do you get rid of red ants in the lawn

Use Nipon, dusted in areas where you see them.

I use the bait stations (Nippon make one) on the lawn. Just leave it near the nest baited with the special gel and it should rid you of the whole nest in a couple of days. I find this preferable to putting powders/sprays directly on to the grass.And wash the soil off with plain copld water before mowing, otherwise you'll have a muddy patch on the lawn!!