Dogwood infestation

What is critter on my dogwood?
On undersides of leaves.
I'm not sure if they're just roosting there, or about to make a meal of my entire tree.
Are they harmless? Or should I get out the Napalm?

Closer view.

Closer.
The tree otherwise looks healthy. Flowered fine this spring.
There are some tiny holes chewed into several leaves, but nothing out of the ordinary.
Any help is appreciated.

They almost look like mealy bugs.

No idea what they are, but that sure would make me nervous. Any insect on a tree tends to bring bad news, or such has been my experience.....

Those look like one of the Cottony Scales, which look like mealybugs too.

Pulvinaria innumerabilis (Cottony Maple Scale) is known on Flowering Dogwood. In fact, anyone who has Johnson & Lyon Insects that Feed on Trees and Shrubs (and if you don't, but want to know about bugs and your plants, you should get) can see great big color pictures that look like Weerobin could have just posted them there.

Notice the specific epithet for this bug: innumerabilis. That ought to suggest something about their fecundity.

A smothering insecticide like light horticultural oil, an insecticidal soap when crawlers emerge, or a systemic insecticide (these are piercing/sucking insects, not chewers) is the order for control. I'd only spray where you see them, since they crawl from place to place - they are not fliers.

Yikes.
The quandary is that the tree is too big to spray (at least, too big for me to spray it).
It's over the top of my two-story house.
And I hate to use a systemic and kill every visiting beneficial insect who wants to visit.
Is there a third alternative?
Will is just suck a little here and there and move to someone else's tree,
or is the tree's survival actually at risk?
I don't care if it looks a little stunted for a season, as long as there's no long term harm.
If the cottony scale is a threat to my dogwood's survival, I guess I'll have to use the systemic.

Only your arborist knows for sure...

That's a big plant to fool with - or not treat properly. I agree about systemic wipe-out-everything - I don't use them for that very reason. Not seeing any more than a leaf or two, I can't offer much but general opinion about your situation.

Scale in and of themselves usually are itinerant pests, but on Flowering Dogwood I wouldn't just brush off any potential effect.

You haven't said whether the pest is spread throughout your plant, or if it is only in an isolated spot. If isolated, then just spray that area. If throughout, maybe invest in professional help. At least, get a recommendation from a professional on your tree.

I think the litte buggers overwinter on twigs, and then start feeding in the spring on the new leaves. They aren't just going to traipse off to greener pastures. You may have the choice to wait till dormant season, and smother them then with a horticultural oil application. That's an efficient method, and less toxic to beneficials et al.

The entire tree appears to be infested.
We have many excellent arborists in our area.
I'll consult one.
Thanks for your help.