Avid is very effective for controlling bamboo mites. The active chemical is abamectin and the main caution to observe is not to spray it around bees because it can also kill them. I have used it on my large collection of bamboo over the last five years and it takes care of the problem. It's an expensive chemical (I paid $125 for an 8 ounce bottle), but that quantity makes up about 400 gallons of spray mixture, and will last me a number of years. As with any chemical, it's good to only spray when absolutely necessary so you don't end up helping some "super mite" evolve. I spray about once a year, and I mix in some horticultural oil, like Stylet, which helps smother the mites. When you spray, try to hit the underside of the leaves as that is where the webs are. However, abamectin has trans-laminar properties, so it will enter the leaf structure and compensate for not hitting every single surface.

Here is a link that might be useful: Abamectin