[Orion]

I've had good luck treating the roots using the Bayer adelgid treatment. You have to catch it before the tree turns brown though. I keep a good scan of all the hemlocks on my property for signs of the darned things. The tree usually gives you some signs it's in trouble before it's too late.

My trees had adelgids visible before treatment, gone after treatment. It may take treating 2 years in a row to completely eradicate, but the treatment definitely kills the adelgids and reverses the spread.