Gordon, thanks for the reply, and the lizards thank you...
You answered part of my questions in that there is a difference bt. harvesters and leaf-cutters. I will do some more research and look for the harvesters, but I don't think the ones in my yard are harvesters. I only have seen them carrying small leaves, like those from mesquite and palo verde. We have pine trees too and I've seen them carrying dead pine needles. They are not a glossy black, but more of a darker version of the other leaf-cutters I've seen. I'll try to get some photos in the near future.
The ants I see attacking bushes and trees are true leaf-cutters. They've even gone into large cedar trees and cut down needles. Because we have a fairly large yard (an acre) and we have lots of trees, etc, the ants are attracted and may come from other people's yards nearby. I've seen them come from pretty far away and it's amazing to see their long line of workers all carrying a piece of leaf or flower petal. There must be thousands in a colony. We rarely have horned lizards (regals) in our yard, so maybe they don't like leaf-cutters. I think the leaf-cutters have a stinger, but I'm not sure. They usually don't pay any attention to me.
Thanks for your help. Glad to see you over here. If anyone would be interested I could try to document some of the inverts in our yard and house. Lots of widows...LOL.