Warbler feeding

On the return leg of my Montana vacation, I stopped at Fort Peck. In the vicinity of the lake are several camp sites. I pulled into one and soon saw a group of these warblers flitting about a tree. They were very excited flying between the trees and twittering away. I don’t know if the lady bugs were the object of the excitement or not. I didn’t see the birds eat the bugs. Other assorted birds were visiting the trees, too. I don’t have a Western bird book with me so I’m uncertain what they are.