They should die, having been removed from their food resource.

Resin

I Googled this:

Quote
The eggs are laid about the time the buds break. About 10 to 14 days later, the nymphs hatch and begin to feed at the bases of the needles. Their feeding causes a pineapple-shaped gall to form in the new twig. The nymphs mature in cells inside the gall until the gall dries out and splits open in summer.
Unquote

So its not in fact crystal clear once the Gall pineapple forms that the insects inside will die if the Gall is removed. Its still possible the Gall acts like a cocoon. Maybe all the feeding is done by the time the Gall is formed? Anyway I have put some Galls in a jar with an air source and I will see what happens - although the insect is probebly too small to see anyway if it does emerge.

I have been growing literally thousands of Norway spruce trees at my timberland in Western MD, and dozens near Winchester, VA (I planted 300 more this year). I see these galls on my spruces from time to time, mostly on the smaller trees. I have never done anything to combat them. Once in a while a tree will have a great many, but I can't see that they cause much, if any damage, and in a year or two they always go away. I guess there is no harm in removing them, unless you fall from a ladder in the effort. I would not wory about them.

However, maybe in some parts of the country they are a problem--I don't know. But I have never owned a tree where they were a problem, and never seen one.

--Spruce