I'm still looking into these things as I've never heard of them but there's quite a bit on them:
Hemlock Woolly Adelgid ( Adelges tsugae )
Balsam Woolly Adelgid ( Adelges piceae )
I'm still trying to find a decent picture of a "typical Adelgid" if there's such a thing as the things are apparently so tiny you can hardly see them in a decent picture.
This is interesting indeed. Enjoy educating yourselves. XD