Hard to control and probably adelgid but looks like mealy bug too. Adelgid has killed most large hemlocks in the Shenandoah Valley. You should use a systemic that is labeled for adelgid. If it kills adelgid it will kill mealy bug. Best of luck.
Got better pix. You can see what flakes off on to the black paper from the elm twig.
The pine is less today as I did spray it with some Neem oil yesterday.
I used some Bayer Tree & Shrub Feed and Protect combination feed and systemic insecticide. It's labeled for adelgid if that's what it is.
I also sprayed some weak Safer soap on the areas.
The stuff in the photo on the left looks like scale and on the right is likely adelgid. The Bayer should do the trick, but be aware that the active ingredient imidcloprid has been identifed with bee decline so don’t spray on anything that flowers.