What is this white stuff?

Pinus ponderosa

Same stuff?

Pinus strobiformis

I'm starting to wonder if this is a growing Cooley gall infection? Which would specifically ID the offending critters as Cooley spruce gall adelgids, or woolly aphids. I applied aphid spray a few days ago, but it looks like the damage may have already been done? Time to prune?

Picea pungens

For comparison, here is a confirmed Cooley gall.

{{gwi:676464}}

Interesting, that the adelgids live on two hosts (Douglas-fir and spruce) to complete their life cycle. See link below.

Here is a link that might be useful: spruce gall