The poor grass in the backyard had been traumatized by something unknown. A bunch of grass died and left some holes in the lawn. The gardeners brought in some patches (May/June) but that didn't help very much and it just kept dying.
We tried to figure out what it was. Not enough water, too much water, fertilizer, what?!! Finally, we saw the little culprits one morning when I hand watered with the hose. They looked like some worms. A trip to Home Depot and some spray and poof, the little boogers went away. It says that it is good for a two months so I'll have to re-apply soon. But for the time being the grass seems to have recovered.
Now, the only thing is to remove the remnants of the wrong type of grass that we used as spot patches.