Beetles released at Echo Park in Dinosaur N.M. have so far chowed down on tammies since May of last year. These beetles (Diorhabda elongata deserticola) have been tested in sites throughout the west for over 20 years. So far, so good. Excellent results, in fact, in sites in Lovelock, NV, and another I can't remember in Cataract Canyon. Of course, the wisdom of introducing one non-native species to control another can be a double edged sword. Only time will tell, and the beetles are extremely picky about where they will live, so they might not make it in Grand Canyon and other areas at all.
Tammies will never be exterminated completely, but it can be controlled, sometimes with great results and less labor than you'd think. And boy does it feel good to yank them out of the ground.